In music and other performing arts, the phrase ad libitum (; Latin for 'at one's pleasure' or 'as you desire'), often shortened to "ad lib" (as an adjective or adverb) or "ad-lib" (as a verb or noun), refers to various forms of improvisation.
The roughly synonymous phrase a bene placito ('in accordance with [one's] good pleasure') is less common but, in its Italian form a piacere, has entered the musical lingua franca (see below).
The phrase "at liberty" is often associated mnemonically (because of the alliteration of the lib- syllable), although it is not the translation (there is no cognation between libitum and liber). Libido is the etymologically closer cognate known in English.
In biology and nutrition, the phrase is used to describe feeding without restriction.
