1620-30; < Latinaperient- (stem of aperiēns opening, present participle of aperīre to open), equivalent to aperi- (apparently ap-, variant of ab-ab- + -eri-) + -ent--ent; the base -eri-, perhaps with an earlier shape *wery- or *twery-, occurs only in this verb and operīre to close (see cover, operculum)