op

UK: /ˈɒp/ US: (op)

WordReference Random House Unabridged Dictionary of American English © 2026

op  (op), n. 

1. Fine Art See op art. 

OP, 

1. Military observation post.

Also, O.P. 
op-, 

1. var. of ob- (by assimilation) before p: oppose.

Op., 

1. Music and Dance opus.

op., 

1. Music and Dance opera.
2. operation.
3. opposite.
4. Music and Dance opus.

O.P., 

1. Military observation post.
2. British Terms, Show Business See opposite prompt. 
Order of Preachers (Dominican).
• Latin Ōrdō Praedicātōrum
3. out of print.
4. overproof.

o.p., 

1. out of print.

Collins Concise English Dictionary © HarperCollins Publishers::

OP abbreviation

1. Ordo Praedicatorum (the Dominicans)
2. organophosphate
3. original poster (on an online discussion forum)

Etymology: (for sense 2) Latin: Order of Preachers

Collins Concise English Dictionary © HarperCollins Publishers::

o.p., O.P. abbreviation

1. out of print

Collins Concise English Dictionary © HarperCollins Publishers::

op. abbreviation

1. operation
2. opus
3. operator