Definitions:
used to link alternatives

introducing a synonym or explanation of a preceding word or phrase

otherwise (used to introduce the consequences of something not being done or not being the case)

introducing an afterthought, usually in the form of a question

either

a logical operation which gives the value one if at least one operand has the value one, and otherwise gives a value of zero.

gold or yellow, as a heraldic tincture

operational research.

oregon (in official postal use).

other ranks (as opposed to commissioned officers).