(Internet slang) Alternative letter-case form of OP (“original post, original poster”).

(slang, among criminal gangs) Alternative form of opp (“opponent; opposition”).

(Australia, informal, transitive) To buy (something) from an op shop. / (Australia, informal, intransitive) To shop at op shops.

(music, abbreviation) Opus. / (abbreviation) Operation. / (abbreviation) Operator. / (abbreviation) Operative. / (abbreviation) A detective. / An operator's license, usually ops

(Cornwall) alley or narrow passage e.g. Tonkin's Ope

(Midwest) an exclamation of surprise; oops

(now dialectal or poetic) Open.

(archaic, transitive, intransitive) To open.

Initialism of Overall Position. / (theater) Initialism of opposite prompt; stage right. / (Internet) Initialism of original poster; the person who started a thread.

(publishing) Abbreviation of out of print. / Abbreviation of overproof. / (video games) Abbreviation of overpowered. / (Internet, music) Initialism of overplayed.