-op·sis \ˈäpsə̇s\noun combining form Etymology: New Latin, from Greek, from opsis appearance, vision — more at optic 1. a.: organism resembling or having a part that resembles a (specified) thing — in generic names < Chilopsis > < Ampelopsis > b.plural-opses: structure resembling a (specified) thing < caryopsis > 2.plural-opses: -opsia