(set theory) The unique set that contains no elements, denoted ∅ or {}.

(transitive) To state; describe; give an account of. / (transitive) To present for consideration; to propose. / (intransitive) To begin a journey or expedition. / (intransitive) To start.

(psychology) A mental predisposition to perceive things in a certain way.

(idiomatic) A social class of wealthy people who travel for pleasure.

Relating to the life style of the jet set.

To follow the life style of the jet set.

(grammar) An established expression whose wording is subject to little or no variation, and which may or may not be idiomatic. / (grammar) An idiomatic expression in general.

A screw with threads along the entire length and no head. Typically, set screws have a hex or slot drive recessed in the threaded length; a grub screw or worm screw.

(idiomatic) Permanent; certain; firm.

To render something permanent, certain, or firm.