1. ad-lib

remark made spontaneously without prior preparation

Example Sentences:
'his ad-libs got him in trouble with the politicians'

2. ad-lib, extemporise, extemporize, improvise, improvize

perform without preparation

Example Sentences:
'he extemporized a speech at the wedding'

• extemporise
• extemporize
• improvise
• improvize

3. ad-lib, extemporaneous, extemporary, extempore, impromptu, off-the-cuff, offhand, offhanded, unrehearsed

with little or no preparation or forethought

Example Sentences:
'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'

• extemporaneous
• extemporary
• extempore
• impromptu
• off-the-cuff
• offhand
• offhanded
• unrehearsed

4. ad-lib, spontaneous, unwritten

said or done without having been planned or written in advance

Example Sentences:
'he made a few ad-lib remarks'

• spontaneous
• unwritten