Vigesimal
Pronunciation : Vi*ges"i*mal
Part of Speech : a.
Etymology : [L. vigesimus twentieth, from viginti twenty.]
Definition : Defn: Twentieth; divided into, or consisting of, twenties or twenty parts. Tylor.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder