1.Definition: causing a sharp and acrid taste experience
"Quinine is bitter"
2.Definition: causing a sharply painful or stinging sensation; used especially of cold
3.Definition: expressive of severe grief or regret
"Shed bitter tears"
4.Definition: harsh or corrosive in tone
5.Definition: marked by strong resentment or cynicism
"Bitter about the divorce"
6.Definition: proceeding from or exhibiting great hostility or animosity
"A bitter struggle", "Bitter enemies"
7.Definition: very difficult to accept or bear
"The bitter truth", "A bitter sorrow"