proportional (adj.)

A type of OPPOSITION recognized in PRAGUE SCHOOL PHONOLOGY, distinguished from ISOLATED. The opposition between /f/ and /v/ in English is proportional, because there are other oppositions in the language which work in parallel, e.g. /s/ and /z/,  and ; on the other hand, the opposition between, say, /v/ and /l/ is isolated – there are no other segments that are contrasted in this particular way, i.e. VOICED LABIO-DENTAL FRICATIVE v. voiced LATERAL.