Definition for Extemporaneous:

• Of a prescription, devised for the occasion, and not according to a standing formula. Of a pharmaceutical preparation, one which must be prepared as required, owing to its tendency to deteriorate on standing, e. g., infusions. [ Lat.]

Synonyms for Extemporaneous:

• adj.

  •improvised (adjective)
  • fake,
  • on impulse,
  • expedient,
  • jamming,
  • automatic,
  • ad hoc,
  • made-up,
  • informal,
  • immediate,
  • free,
  • snap,
  • toss off,
  • unplanned,
  • winging it,
  • by ear,
  • Improvisatory,
  • on-the-spot,
  • toss out,
  • makeshift.
  •impulsive (adjective)
  • improvised,
  • hasty,
  • reflexive,
  • Unmeditated,
  • abrupt,
  • unprompted,
  • instantaneous,
  • rash,
  • ill-considered.
  •unprepared (adjective)
  • haphazard.

• n.

  •
  • instinctive,
  • coincidental,
  • involuntary.
  •extemporaneous (noun)
  • extempore,
  • extemporary,
  • offhanded,
  • offhand,
  • unprepared,
  • unrehearsed.

• Other synonyms:

  •extemporaneous
  • cuff.
  •informal
  • candid.
  •Other relevant words:
  • headlong,
  • momentary,
  • accident,
  • unguarded,
  • collar,
  • Unconcocted,
  • Undeliberated,
  • speck,
  • unconscious,
  • ready,
  • natural,
  • contingency,
  • Indeliberate,
  • vicar,
  • worker,
  • sudden,
  • soupcon,
  • unwritten,
  • proxy,
  • mite,
  • unready,
  • impetuous,
  • Unbegun,
  • summary,
  • haste,
  • Improvisate,
  • madcap,
  • reckless,
  • unpredictable,
  • touch,
  • procurator,
  • freewill,
  • precipitate,
  • devil-may-care,
  • unhatched,
  • emotional,
  • caught off balance,
  • Extemporized,
  • surprised,
  • jury-rigged,
  • Improvisatorial,
  • tripped up,
  • unorganized,
  • Unarranged,
  • instant,
  • unguided,
  • apprehension,
  • deputy,
  • taken aback,
  • wild,
  • foolhardy,
  • quick,
  • improvise,
  • Unmanufactured,
  • emergency,
  • brisk,
  • arrest,
  • stopgap,
  • unannounced,
  • voluntary,
  • temp,
  • pinch,
  • crisis,
  • unprimed,
  • unconsidered,
  • brief,
  • exigency,
  • taken by surprise,
  • caught short,
  • last-minute,
  • hint,
  • caught napping,
  • unpretentious,
  • unmade,
  • Extemporal.

Antonyms for Extemporaneous:

• adj.

  • improvised
    planned, deliberate, Rehearsed, premeditated, prepared.
  • Other antonyms:
    intended, intentional, considered, written, studied, elaborated, read, premeditated, planned, premeditative, Rehearsed.