(idiomatic) People will be dealt with in the order they arrive.

Alternative spelling of first-come-first-served

plural of firstborn

plural of firstling

A country's most important city, usually the capital.

(idiomatic) second place.

(law, informal) the concept that a dog is not considered dangerous until it has bitten someone.

(mathematics, logic) Of one of a series of models, languages, relationship, forms of logical discourse, etc., being the simplest one or the first in a sequence. / Of fundamental importance.

The leading woman in a specified field of endeavor. / Alternative spelling of First Lady

The wife of the chief executive of a nation; especially the wife of the President of a country; or a woman (e.g. a relative) who takes on similar public duties, as when the chief executive is unmarried.