Of first resort. / Of prime quality or importance. / At the lowermost supervisory level.

(blackjack) A form of hole carding in which a player peeks at the hole card as the dealer checks it.

The dog belonging to the President of the United States of America

Used to indicate that a statement, though not necessarily entirely accurate or without exceptions, is good enough for basic or preliminary purposes; more or less; basically.

As the first step or stage; first.

plural of first night

(obsolete, literally) at the first attack or engagement of battle / (obsolete) at first encounter, at the start

(civil law) A prototype or archetype. / (innovation, manufacturing) A preproduction model, initial sample or pilot model.

plural of first article

Priority on the use of somebody or something, especially an actor if required in a production.