Learner's definition of UNPLEASANT
[more unpleasant; most unpleasant]
not pleasant or enjoyable
causing discomfort or pain
I stopped taking the drug because of its unpleasant side effects.
There was an unpleasant smell/odor coming from the basement.
The weather is so unpleasant here.
I was unpleasantly surprised to discover that I couldn't find my keys.
The juice was unpleasantly sour.
Our vacation started unpleasantly with long delays and bad weather.