I. (ˈ)adˈlibəd.əm adverb
Etymology: New Latin, in accordance with one's wishes
: ad lib
II. (ˈ) ̷ ̷| ̷ ̷ ̷ ̷ ̷ ̷ adjective
: variable according to a performer's pleasure : omissible — abbr. ad lib ; used especially of music; distinguished from obbligato