Definify.com

Webster 1913 Edition

Adj.

[L.

impar

unequal + E.

syllabic

: cf. F.

imparisyllabique

(Gram.)

Not consisting of an equal number of syllables;

as, an

imparisyllabic

noun, one which has not the same number of syllables in all the cases

; as, lapis, lapidis; mens, mentis.

imparisyllabic ‎(not comparable)

Not having the same number of syllables in all its inflections (especially of Greek or Latin nouns); for example, the Latin word pars, which has the genitive form partis.

not having the same number of syllables

imparisyllabic ‎(plural imparisyllabics)

An imparisyllabic noun.
- 1974 (revised 1989), Peter Rickard, A History of the French Language, Routledge 2002, pp. 50-1:
  An adjectival type corresponding phonetically to the masculine third declension imparisyllabics is represented by some O.F. survivals of Latin comparative forms