un

opposite, against

Spelled un · un- 'not, opposite of'

Old English un says not: undaunted means not intimidated, unbiased means not slanted, and unruly means not governed.

Words built from it

unruly — disorderly and hard to control
un- (not) + ruly (governed by rule)
unbiased — showing no prejudice; fair
un- (not) + biased (having a slant or bias)
unassuming — modest, not pretentious
un- (not) + assuming (acting superior, presumptuous)
uncanny — strange in an unsettling way
un- (not) + canny (familiar, known, from 'ken')
undaunted — not discouraged by difficulty
un- (not) + daunted (intimidated, from Latin domitare 'to tame')
unequivocal — leaving no doubt; clear
un- (not) + equivocal (ambiguous, open to two meanings)
unscrupulous — without moral principles
un- (not) + scrupulous (careful of ethics, from Latin scrupulus)

unanimous — from Latin unus 'one' plus animus 'mind' — the 'un' here means 'one,' not 'not'
uniform — from Latin unus 'one' + forma 'shape,' not the Old English un- prefix
mundane — from Latin mundus 'world,' not the Old English un- prefix