Definition of unpremeditated:
unstudied, arbitrary, ad hoc, by accident, unintentional, reflex, off-the-cuff, inadvertent, chance, offhanded, unwitting, offhand, spur-of-the-moment, unintended, involuntary, automatic, snap, fluky, unplanned, impulsive, incidental, ad-lib, planned, casual, extemporary, down and dirty, instinctive, unprepared, random, improvisational, fortuitous, accidental, extempore, coincidental.
If ever the day should come when men and women shall be content to signal their perception of humour by the natural smile, and shall keep the laugh for its own unpremeditated act, shall laugh seldom, and simply, and not thrice at the same thing- once for foolish surprise, and twice for tardy intelligence, and thrice to let it be known that they are amused- then it may be time to persuade this laughing nation not to laugh so loud as it is wont in public.- "Essays", Alice Meynell.
52. " Words are obviously voluntary signs: and they are also arbitrary; excepting a few simple sounds expressive of certain internal emotions, which sounds being the same in all languages, must be the work of nature: thus the unpremeditated tones of admiration are the same in all men."- "The Grammar of English Grammars", Goold Brown.
- "The Power and the Glory", Grace MacGowan Cooke.