Meaning : To certain extent or degree.
Example :
Pretty big.
Pretty bad.
Jolly decent of him.
The shoes are priced reasonably.
He is fairly clever with computers.
Synonyms : fairly, jolly, middling, moderately, passably, reasonably, somewhat
To a degree that exceeds the bounds or reason or moderation.
His prices are unreasonably high.Meaning : Pleasing by delicacy or grace. Not imposing.
Example :
Pretty girl.
Pretty song.
Pretty room.
Meaning : (used ironically) unexpectedly bad.
Example :
A pretty mess.
A pretty kettle of fish.