1.
Un- is added to the beginning of adjectives, adverbs, and nouns, in order to form words that have the opposite meaning.
My father was an unemployed labourer...
He had sensed his mother’s unhappiness.
PREFIX
2.
Un- is added to the beginning of a verb that describes a process, in order to form another verb that describes the reverse of that process.
He undressed and draped his clothes neatly over the back of the chair...
She was anxious for me to unwrap the other gifts.
PREFIX
3.
Un- is added to the beginning of the past participle of a verb, in order to form an adjective that means that the process described by the verb has not happened.
The theory remains untested...
Dealers across the country continue to complain about huge stocks of unsold cars.
PREFIX