(literally and figuratively) The state, quality, or condition of being up / (quantum mechanics) The property of being an up quark.

(informal) Legitimate; honest; upright.

Alternative spelling of on the up-and-up

Alternative form of grownupness

The quality of being made-up, or invented.

(informal) The state or condition of being messed-up.

(idiomatic) Willing to participate in; interested in. / (idiomatic) Being or due to be evaluated, inspected, judged, considered, sold, etc., in the stated circumstances or by the stated method.

(idiomatic) To do or be involved in doing; to do (often something mischievous or inappropriate). / (idiomatic) To depend on, to be the choice of.

simple past tense and past participle of up

(electronics) Initialism of uninterruptible power supply/source / Initialism of ultraviolet photoelectron spectroscopy. / (biochemistry) Initialism of ubiquitin-proteasome system.