\Un-\ [OE. un-, on-, the unaccented form of the accented
prefix and- (cf. {Answer}); akin to D. ont-, G. ent-, OHG.
int-, Goth. and-. See {Anti-}.]
An inseparable verbal prefix or particle. It is prefixed:
(a) To verbs to express the contrary, and not the simple
    negative, of the action of the verb to which it is
    prefixed; as in uncoil, undo, unfold.
(b) To nouns to form verbs expressing privation of the thing,
    quality, or state expressed by the noun, or separation
    from it; as in unchild, unsex. Sometimes particles and
    participial adjectives formed with this prefix coincide
    in form with compounds of the negative prefix un- (see 2d
    {Un-}); as in undone (from undo), meaning unfastened,
    ruined; and undone (from 2d un- and done) meaning not
    done, not finished. Un- is sometimes used with an
    intensive force merely; as in unloose.
Note: Compounds of this prefix are given in full in their
      proper order in the Vocabulary.

\Un-\ [OE. & AS. un-; akin to OFries. un-, D. on-, OS.,
OHG., & G. un-, Icel. [=o]-, [=u]-, Sw. o-, Dan. u-, W. an-,
L. in-, Gr. ?, ?, Skr. an-, a-. [root]193. Cf. {A-} not {In-}
not, No, adv.]
An inseparable prefix, or particle, signifying not; in-;
non-. In- is prefixed mostly to words of Latin origin, or
else to words formed by Latin suffixes; un- is of much wider
application, and is attached at will to almost any adjective,
or participle used adjectively, or adverb, from which it may
be desired to form a corresponding negative adjective or
adverb, and is also, but less freely, prefixed to nouns. Un-
sometimes has merely an intensive force; as in unmerciless,
unremorseless.
I . Un- is prefixed to adjectives, or to words used
  adjectively. Specifically:
(a) To adjectives, to denote the absence of the quality
    designated by the adjective; as,
(b) To past particles, or to adjectives formed after the
    analogy of past particles, to indicate the absence of the
    condition or state expressed by them; as,