(mathematics) an interval in the real number line which does not contain its supremum and infimum. If specified by a pair of real numbers, then it consists of all the points on the real line whose values lie strictly between those two real numbers.

An unannounced or lightly announced business opening, instead of or prior to a grand opening.

plural of bottle opener

plural of open book

(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.

simple past tense and past participle of open fire

present participle of open fire

simple past tense and past participle of open source