In linguistics, a conservative form, variety, or modality is one that has changed relatively little over its history, or which is relatively resistant to change. It is the opposite of innovative or advanced forms or varieties, which have undergone relatively larger or more recent changes. On the other hand, an archaic language is chronologically old.
A conservative linguistic form, such as a word, is one that remains closer to an older form from which it evolved, relative to cognate forms from the same source. For example, the Spanish word caro and the French word cher both evolved from the Latin word c?rum. The Spanish word, which is more similar to the common ancestor, is more conservative than its French cognate.
A language or language variety is said to be conservative if it has fewer innovations (in other words, more conservative forms) than related varieties do. For example, Icelandic is, in some aspects, more similar to Old Norse than other languages that evolved from Old Norse, including Danish, Norwegian, or Swedish, while Sardinian (especially the Nuorese dialects) is regarded by many linguists to be the most conservative Romance language. In fact, recent studies regarding the stability of modern Icelandic appear to confirm its status as "stable". Therefore, Icelandic and Sardinian are considered relatively conservative languages. Likewise, some dialects of a language may be more conservative than others. Standard varieties, for example, tend to be more conservative than nonstandard varieties, since education and codification in writing tend to retard change.
Writing is generally said to be more conservative than speech since written forms generally change more slowly than spoken language does. That helps explain inconsistencies in writing systems such as that of English; since the spoken language has changed relatively more than has the written language, the match between spelling and pronunciation is inconsistent. (See Great Vowel Shift.)
A language may be conservative in one respect while simultaneously innovative in another. Bulgarian and Macedonian, closely related Slavic languages, are innovative in the grammar of their nouns, having dropped nearly all vestiges of the complex Slavic case system; at the same time, they are highly conservative in their verbal system, which has been greatly simplified in most other Slavic languages. English, which is one of the more innovative Germanic languages in most respects (vocabulary, inflection, vowel phonology, syntax), is nevertheless conservative in its consonant phonology, retaining sounds such as (most notably) and (th), which remain only in English, Icelandic and Scots.
Conservative languages are often thought of as being more complex grammatically (or at least morphologically) than innovative languages. That is largely true for Indo-European languages, where the parent language had an extremely complex morphology and the dominant pattern of language change has been simplified. On the other hand, a number of Arabic varieties commonly considered innovative, such as Egyptian Arabic, have developed a complex agglutinative system of verbal morphology out of the simpler system of Classical Arabic.
In the 6th century AD, Classical Arabic was a conservative Semitic language compared with Classical Syriac, which was spoken at the same time; Classical Arabic strongly resembles reconstructed Proto-Semitic, and Syriac has changed much more. Compared to closely related modern Northeastern Neo-Aramaic, which is not necessarily directly descended from it, Classical Syriac is still a highly archaic language form.
Georgian has changed remarkably little since the Old Georgian period (the 4th/5th century AD).
A roughly analogous concept in biology is living fossil.