, concerned with viewing a language
at a single stage in time. Opposite to diachronic
, which looks through the history of a language. The synchronic features of a language often have diachronic explanations.
For example, English plurals are synchronically regular, using -s, -es and pronounced according to a clear rule, except for a handful of words that have no systematic justification. But historically, the -en and umlaut classes were also regular and productive.
In many varieties of English, including standard British, the present participle has the ending -ing after most words, but (in speech) -ring after some vowels. Examples include bar, butter, cure pronounced (in SAMPA notation) [ba:, bat@, kjU@]. Synchronically it is just a class of vowels that take the ending pronounced -ring, but diachronically it is of course just those vowels that arose from the disappearance of a consonant [r]. This is obvious because the r is still present in the spelling and is still pronounced in other dialects. But the modern situation is not just a relic of the history. Words that never had a final r, such as gnaw, draw, are now candidates for the rule "if it ends in [O:], add [rIN]". Some speakers may treat pawing and pouring as the same; if they do, they have a revised synchronic rule that is not the same as the diachronic process that gave rise to it.
Whole systems can be structurally different at different times. The labiodental fricatives [f] and [v] are a pair differing by voice, just like [s ~ z] or [p ~ b], but in Old English they were varieties of the same phoneme (basic sound), written with F, and pronounced [v] between vowels, giving a distribution as in full, liver, calf. With the input of French words in Middle English, including many beginning with V, they came to be contrastive, as in file, vile. What had been one phoneme split into two, with a restructuring of the phonemic system.
Term coined by Ferdinard de Saussure.