to function or cause (e.g. a machine) to function; to work
to exert power or influence; to act or produce a desired effect
There were several factors operating against our success
to produce a desired effect
to be in effect; to function
to be in action; specif to carry out trade or business
(often + on) to perform surgery
to carry on a military or naval action or mission
to cause (e.g. a machine) to function
to put or keep (e.g. a business) in operation; to manage (an enterprise)
to cause (something) to happen
[Latin operatus, past part. of operari to work, from oper-, opus work]