Bitterness


is,


Extreme enmity; hatred;
stubborn grudge.


...Let all bitterness, and wrath, and anger, and clamour,
and evil- speaking be put away from you, with all malice:
And be ye kind to one another,
tenderhearted, forgiving one another,
even as God for Christ's sake
hath forgiven you.

Ephsians 4:31 & 32