Unpleasant means not nice at all. An unpleasant smell, an unpleasant surprise, he was rather unpleasant about it.
In British English it is a considerable understatement: describing somebody as unpleasant usually means a great deal more than the word says. Unpleasantness is a euphemism for a row or a scandal — after all the unpleasantness — and is one of the most evasive nouns in the language. Note that unpleasant covers smells, weather, tasks and people equally, which is unusual reach for one adjective.
1adjectiveunpleasantNot nice at all.
“It was an unpleasant job and somebody had to do it.”
synonyms: disagreeable, nasty
2adjectiveunkindUnkind or rude, of a person.
“He was unpleasant about it in front of everybody.”
unpleasant is a quality of nastiness.
The word is un- plus pleasant, from Old French plaisant, from Latin placere, to please. English attached its own native negative prefix to a French adjective, which it does constantly and without hesitation.
Middle English
unplesaunt
English, today
unpleasant
From Middle English unplesaunt, equivalent to un- + pleasant.
Etymology from Wiktionary, CC BY-SA