1. With little or no preparation or forethought
   "an extemporary lecture"
   - ad-lib, extemporaneous, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed

See also: extemporarily, unprepared

• irresistibility
• irresistible
• irresistible impulse
• irresistibleness
• irresistibly
• irresolute
• irresolutely
• irresoluteness
• irresolution
• irresolvable
• irrespective
• irresponsibility
• irresponsible
• irresponsibleness
• irresponsibly
• irresponsive
• irretrievable
• irretrievably
• irreverence
• irreverent
• irreverently
• irreversibility
• irreversible
• irreversible process
• irreversibly