ad-lib

(noun) remark made spontaneously without prior preparation. Example: "His ad-libs got him in trouble with the politicians."

(verb) perform without preparation. Synonyms: improvise, improvize, extemporize, extemporise. Example: "He extemporized a speech at the wedding."

(adj) with little or no preparation or forethought. Synonyms: extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed. Examples: "His ad-lib comments showed poor judgment." "An extemporaneous piano recital." "An extemporary lecture." "An extempore skit." "An impromptu speech." "Offhand excuses." "Trying to sound offhanded and reassuring." "An off-the-cuff toast." "A few unrehearsed comments."

(adj) said or done without having been planned or written in advance. Synonyms: spontaneous, unwritten. Example: "He made a few ad-lib remarks."

(adv) without advance preparation. Synonyms: ad lib, ad libitum, spontaneously, impromptu. Example: "He spoke ad lib."