The Collaborative International Dictionary
Ad libitum \Ad lib"i*tum\ At one's pleasure; as one wishes.
Ad libitum is Latin for "at one's pleasure"; it is often shortened to "ad lib" (as an adjective or adverb) or "ad-lib" (as a verb or noun). The roughly synonymous phrase a bene placito ("in accordance with [one's] good pleasure") is less common but, in its Italian form a piacere, 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.
Usage examples of "ad libitum".
These facts may be used ad libitum, only keeping my name out of sight.
It's part of the hallucination too, but that doesn't matter, for when you take it the gates to the next dream open before you, and so on ad libitum.
Though his sword and dagger had perforce been laid aside before coming into the commander's presence, he still looked able to reduce the population barehanded ad libitum.
It is taken in wineglassful doses, which may be repeated ad libitum.
Or better, with unobtrusive signals of hand and whip, so they look like they're really doing it ad libitum.