plural of bottle opener

(education) Referring to exams in which external resources such as textbooks, glossaries, study notes, calculators, etc. may be used.

(idiomatic) Something of which salient aspects are obvious or easily interpreted.

plural of open cluster

plural of open book

plural of open compound

(uncountable) A chess opening characterized by the moves 1.e4 e5, in which both White and Black move their king's pawn to the fourth rank with their first move.

(television) An opening segment shown before the opening credits.

plural of cold open

(idiomatic, humorous, in hypothetical constructs) Any kind of event or activity that may contribute to one's self-promotion or visibility in society.