/ Dictionary / Index S semicylinder: Meaning and Definition of Find definitions for: sem•i•cyl•in•der Pronunciation: (sem"ē-sil'in-dur, sem"ī-), [key] — n. half of a cylinder divided lengthwise. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. semicrystalline semidaily Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language