Bit"ter*ness (&?;), n. [AS. biternys; biter better + -nys = -ness.] 1. The quality or state of being bitter, sharp, or acrid, in either a literal or figurative sense; implacableness; resentfulness; severity; keenness of reproach or sarcasm; deep distress, grief, or vexation of mind.

The lip that curls with bitterness.
Percival.

I will complain in the bitterness of my soul.
Job vii. 11.

2. A state of extreme impiety or enmity to God.

Thou art in the gall of bitterness, and in the bond of iniquity.
Acts viii. 23.

3. Dangerous error, or schism, tending to draw persons to apostasy.

Looking diligently, . . . lest any root of bitterness springing up trouble you.
Heb. xii. 15.

• the quality of having a bitter taste
  
• the quality of feeling bitter; acrimony, resentment