In unfavourable sense: To spend, consume, employ uselessly or without adequate result. (Now the most prominent use.) absol.

intransitive. Of persons. With out: To rush, launch out, into excess of any kind; to break out into violent language; to squander one's…

To spend (money, goods, etc.) recklessly, prodigally, or lavishly; to expend extravagantly, profusely, or wastefully. Also const. on.

to play the prodigal: to be recklessly wasteful or lavish; to act like a prodigal (sense B. 2).

intransitive. To lash out; to strike out violently. In earliest use figurative: to break out into excess; to be extravagant, exaggerate. Cf. overlash…

intransitive. To deal carelessly or wastefully (with property, resources). Obsolete.

to light (also burn) the candle at both ends: to consume or waste in two directions at once.

To go to extravagance in.