Free variation
In linguistics, free variation is the phenomenon of two (or more) sounds or forms appearing in the same environment without a change in meaning and without being considered incorrect by native speakers. Sociolinguists argue that describing such variation as "free" is very often a misnomer, since variation between linguistic forms is usually constrained probabilistically by a range of systematic social and linguistic factors, not unconstrained as the term "free variation" suggests. The term remains in use in studies focused primarily on language as systems (e.g. phonology, morphology, syntax), however, since "[t]he fact that variation is 'free' does not imply that it is totally unpredictable, but only that no grammatical principles govern the distribution of variants." Effects When phonemes are in free variation, speakers are sometimes strongly aware of the fact (especially if such variation is noticeable only across a dialectal or sociolectal divide), and will note, for example, that tomato is pronounced differently in British and American English ( and respectively), or that either has two pronunciations that are distributed fairly randomly. However, only a very small proportion of English words show such variations. In the case of different realizations of the same phoneme, however, free variation is exceedingly common