Meaning of UN- in English

UN-

I. ˌən, often ˈən before ˈ- stressed syllable prefix

Etymology: Middle English, from Old English; akin to Old High German un- un-, Latin in-, Greek a-, an-, Old English ne not — more at no

1. : not : in- , non- — in adjectives formed from adjectives

un ambitious

un skilled

or participles

un dressed

in nouns formed from nouns

un availability

and rarely in verbs formed from verbs

un be

— sometimes in words that have a meaning that merely negates that of the base word and are thereby distinguished from words that prefix in- or a variant of it (as im- ) to the same base word and have a meaning positively opposite to that of the base word

un artistic

un moral

2. : opposite of : contrary to — in adjectives formed from adjectives

un constitutional

un graceful

un mannered

or participles

un believing

and in nouns formed from nouns

un rest

II. prefix

Etymology: Middle English, from Old English un-, on-, alteration of and- against — more at ante-

1. : do the opposite of : reverse (a specified action) : de- 1a, dis- 1a — in verbs formed from verbs

un bend

un dress

un fold

2.

a. : deprive of : remove (a specified thing) from : remove — in verbs formed from nouns

un frock

un sex

b. : release from : free from — in verbs formed from nouns

un hand

c. : remove from : extract from : bring out of — in verbs formed from nouns

un bosom

d. : cause to cease to be — in verbs formed from nouns

un man

3. : completely

un loose

Merriam-Webster's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.