Translation memory

From Academic Kids

A translation memory, or TM, is a software program designed as an aid for human translators.

Translation memories are also known as translation memory managers (TMM).

Translation memories are typically used in conjunction with a word processing program, a terminology management system, a multilingual dictionary, and even raw machine translation output.

A translation memory consists of a database of text segments in a source language and their translations in one or more target languages. These segments can be individual words or multiword phrases.

Research indicates that many companies producing multilingual documentation are using translation memory systems.


Using Translation Memories

First the translator supplies a source text (that is, a text to be translated) to the translation memory. The program will then scan the text, trying to find segments in its database which it will use to generate a partly translated output text. This text is presented to the translator for review. The translator can accept the suggestion, reject it or make modifications and use the modified version. In this case, the modified version is recorded and saved in the database.

Some translation memories attempt only literal matching, that is to say that they can only retrieve segments of text that match entries in the database exactly, while others employ fuzzy matching algorithms to retrieve similar segments, which are presented to the translator with differences flagged.

The flexibility and robustness of the matching algorithm largely determine the performance of the translation memory, although for some applications the recall rate of exact matches can be high enough to justify the literal approach.

Segments where no match is found will have to be translated by the translator manually. These new segments are stored in the database where they can be used for future translations.

Translation memories work best on texts which are highly repetitive, such as technical manuals. They are also helpful for making incremental changes to texts, corresponding, for example, to minor product changes. Traditionally translation memories are not considered appropriate for literary or creative texts, for the simple reason that there is so little repetition in the language used.

If a translation memory is used consistently on appropriate texts over a period of time, they can save translators considerable work.

Main Benefits

Translation memory managers are most suitable for translating technical documentation and documents containing specialized vocabularies. Their benefits include:

  • Ensuring that the translated documents are consistent, including common definitions, phrasings and terminology. This is important when different translators are working on a single project.
  • Accelerating the overall translation process; since translation memories "remember" previously translated material, translators have to translate it only once.
  • Reducing costs of long-term translation projects; for example the text of manuals, warning messages or series of documents needs to be translated only once and can be used several times.
  • For large documentation projects, savings (in time or money) thanks to the use of a TM package may already be apparent even for the first translation of a new project, but normally such savings are only apparent when translating subsequent versions of a project that was translated before using translation memory.

Main Obstacles

The main problems hindering wider use of translation memory managers include:

  • The concept of "translation memories" is based on the premise that sentences used in previous translations can be "recycled". However, a guiding principle of translation is that the translator must translate the message of the text, and not its component sentences.
  • Translation memory managers do not easily fit into existing translation or localization processes. In order to take advantages of TM technology, the translation processes must be redesigned.
  • Translation memory managers do not presently support all documentation formats, and filters may not exist to support all file types.
  • There is a learning curve associated with using translation memory managers, and the programs must be customized for greatest effectiveness.
  • In case where all or part of the translation process is outsourced or handled by freelance translators working off-site, the off-site workers require special tools to be able to work with the texts generated by the translation memory manager.
  • Full versions of many translation memory managers can cost from $500 to $2,500 (US) per seat, which can represent a considerable investment (although lower cost programs are also available). However, some developers produce free or low-cost versions of their tools with reduced feature sets that individual translators can use to work on projects set up with full versions of those tools. (Note that there are freeware and shareware TM packages available, but none of these has yet gained a large market share.)
  • The costs involved in importing the user's past translations into the translation memory database, training, as well as any add-on products may also represent a considerable investment.
  • Maintenance of translation memory databases still tends to be a manual process in most cases, and failure to maintain them can result in significantly decreased usability and quality of TM matches.
  • As stated previously, translation memory managers may not be suitable for text that lacks internal repetition or which does not contain unchanged portions between revisions. Technical text is generally best suited for translation memory, while marketing or creative texts will be less suitable.
  • The quality of the text recorded in the translation memory is not guaranteed; if the translation for particular segment is incorrect, it is in fact more likely that the incorrect translation will be reused the next time the same source text, or a similar source text, is translated, thereby perpetuating the error.

Functions of a Translation Memory (TM)

The following is a summary of the main functions of a Translation Memory, as described on Design and function of translation memory (

Off-line functions


This function is used to transfer a text and its translation from a text file to the TM. Import can be done from a raw format, in which an external source text is available for importing into a TM along with its translation. Sometimes the texts have to be reprocessed by the user. There is another format that can be used to import: The native format. This format is the one that uses the TM to save translation memories in a file.


The process of analysis is developed through the following steps:

Textual parsing
It is very important to recognize punctuation in order to distinguish for example the end of sentence from abbreviation. So markup is a kind of pre-editing. Usually, the materials which have been processed through translators' aid programs contain mark-up, as the translation stage is embedded in a multilingual document production line. Other special text elements may be set off by mark-up. There are special elements which do not need to be translated, such as proper names and codes, while others may need to be converted to native format.
Linguistic parsing
The base form reduction is used to prepare lists of words and a text for automatic retrieval of terms from a term bank. On the other hand, syntactic parsing may be used to extract multi-word terms or phraseology from a source text. So parsing is used to normalise word order variation of phraseology, this is which words can form a phrase.
Its purpose is to choose the most useful translation units. Segmentation is like a type of parsing. It is done monolingually using superficial parsing and alignment is based on segmentation. If the translators correct the segmentations manually, later versions of the document will not find matches against the TM based on the corrected segmentation because the program will repeat its own errors. Translators usually proceed sentence by sentence, although the translation of one sentence may depend on the translation of the surrounding ones.
It is the task of defining translation correspondences between source and target texts. There should be feedback from alignment to segmentation and a good alignment algorithm should be able to correct initial segmentation.
Term extraction
It can have as input a previous dictionary. Moreover, when extracting unknown terms, it can use parsing based on text statistics. These are used to estimate the amount of work involved in a translation job. This is very useful for planning and scheduling the work. Translation statistics usually count the words and estimate the amount of repetition in the text.


Export transfers the text from the TM into an external text file. Import and export should be inverses.

Online functions

When translating, one of the main purposes of the TM is to retrieve the most useful correspondences in the memory so that the translator can choose the best one. The TM must show both the source and target text pointing out the identities and differences.


We can retrieve from the TM one or more matching correspondences.

Exact match
We talk about exact matches when the match between the current source segment and the stored one has been a character by character match. When translating a sentence, an exact match means the same sentence has been translated before. Exact matches are also called "100% matches".
In Context Exact (ICE) match
An ICE match is an exact match that occurs in exactly the same context, that is, the same location in a paragraph. Context is often defined by the surrounding sentences and attributes such as document file name, date, and permissions.
Fuzzy match
When the match has not been exact, it is a "fuzzy" match. Some systems assign percentages to these kind of matches, in which case a fuzzy match is greater than 0% and less than 100%. Those figures are not comparable across systems unless the method of scoring is specified.


A TM is updated with a new translation when a it has been accepted by the translator. As always in updating a database, there is the question what to do with the previous contents of the database. A TM can be modified by changing or deleting entries in the TM.

Automatic Translation

Translation memories can do retrieval and substitution automatically without the help of the translator.

Automatic retrieval
A TM features automatic retrieval and evaluation of translation correspondences in a translator's workbench.
Automatic substitution
Exact matches come up in translating new versions of a document. When you translate automatically, you cannot check the translation against the original so if there are any mistakes in the original, they will carry over.


When networking during the translation it is possible to translate a text efficiently together with a group of translators. This way, the translations entered by one translator are available to the others. Moreover, if translation memories are shared before the final translation, the mistakes made by one translator will easily be corrected.

History of Translation Memories

The concept behind translation memories is not recent — university research into the concept began in the late 1970s, and the earliest commercializations became available in the late 1980s — but they became commercially viable only in the late 1990s.

See also

External links

Commercial translation memory packages

References and interesting links

de:Translation Memory es:memoria de traducción fr:Mémoire de traduction


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