unrehearsed β to practice (a musical composition, a play, a speech, etc.) in private prior to a public presentation.
impromptu β made or done without previous preparation: an impromptu address to the unexpected crowds.
ad-lib β If you ad-lib something in a play or a speech, you say something which has not been planned or written beforehand.
spontaneous β coming or resulting from a natural impulse or tendency; without effort or premeditation; natural and unconstrained; unplanned: a spontaneous burst of applause.
off-the-cuff β with little or no preparation; extemporaneous; impromptu: a speaker with a good off-the-cuff delivery.
improvised β made or said without previous preparation: an improvised skit.
ad hoc β An ad hoc activity or organization is done or formed only because a situation has made it necessary and is not planned in advance.
automatic β An automatic machine or device is one which has controls that enable it to perform a task without needing to be constantly operated by a person. Automatic methods and processes involve the use of such machines.
improvisatory β of, relating to, or characteristic of an improvisation or improvisator.
informal β without formality or ceremony; casual: an informal visit.
jamming β to press, squeeze, or wedge tightly between bodies or surfaces, so that motion or extrication is made difficult or impossible: The ship was jammed between two rocks.
made-up β concocted; falsely fabricated or invented: a made-up story.
makeshift β a temporary expedient or substitute: We used boxes as a makeshift while the kitchen chairs were being painted.
off the cuff β with little or no preparation; extemporaneous; impromptu: a speaker with a good off-the-cuff delivery.
offhand β cavalierly, curtly, or brusquely: to reply offhand.
on-the-spot β done or occurring at the time or place in question: an on-the-spot recording.
snap β to make a sudden, sharp, distinct sound; crack, as a whip; crackle.
spur-of-the-moment β occurring or done without advance preparation or deliberation; extemporaneous; unplanned: a spur-of-the-moment decision.
unplanned β a scheme or method of acting, doing, proceeding, making, etc., developed in advance: battle plans.
unpremeditated β done deliberately; planned in advance: a premeditated murder.
unprepared β properly expectant, organized, or equipped; ready: prepared for a hurricane.
unstudied β not studied; not premeditated or labored; natural; unaffected.
throwaway β made or intended to be discarded after use or quick examination: a throwaway container; a throwaway brochure.
autoschediastic β offhand, with little forethought or preparation
fake β to lay (a rope) in a coil or series of long loops so as to allow to run freely without fouling or kinking (often followed by down).
toss off β to throw, pitch, or fling, especially to throw lightly or carelessly: to toss a piece of paper into the wastebasket.
artless β Someone who is artless is simple and honest, and does not think of deceiving other people.
instinctive β of, relating to, or of the nature of instinct.
naive β having or showing unaffected simplicity of nature or absence of artificiality; unsophisticated; ingenuous.
natural β existing in or formed by nature (opposed to artificial): a natural bridge.