(Canada) An illegal marijuana-growing operation, usually indoors.

plural of grow operation

Alternative form of operations research

(arithmetic) Any of the four basic operators in arithmetic, namely addition, subtraction, multiplication and division.

(calculus) A differential operator that preserves mathematical smoothness.

plural of operating theatre

plural of operating room

In the work (already) cited or quoted. Used, typically in footnotes and endnotes, to cite in an abbreviated form a source that has been cited previously; frequently abbreviated as op. cit.

plural of smooth operator

A covert operation typically involving activities that are highly clandestine and outside of standard military protocol.