Ad Libitum

Ad libitum, abbreviated ad lib., is Latin for ‘at pleasure’ or ‘at liberty’. The marking grants the performer freedom — usually with respect to tempo (the music may be played freely, without strict pulse), but sometimes also with respect to ornamentation, repeats, or even content.

In its most common modern usage, ad libitum means ‘play this passage freely’. The performer may use rubato, ornament melodic lines, or take other liberties not specified in the score. Cadenzas in concertos are essentially ad libitum passages.

The marking is also used in 18th-century scores to indicate optional instruments — ‘oboe ad libitum’ means the oboe part may be omitted or substituted as the performance circumstances require. In jazz lead sheets, ‘ad lib’ at the end of a chart invites the player to improvise freely.

Latin, ‘at pleasure’ — ad (‘at’) + libitum (‘pleasure, will’), from libet (‘it pleases’). Compare English libido.

Read context. Ad libitum on a melodic line invites rubato and ornamentation; on a tempo direction it invites flexible pulse; on an instrument label it indicates optionality. The freedom granted is matched to the situation.