the mind > emotion > suffering > mental anguish or torment > bitterness of heart > [adjective] > expressing or betokening bitterness (3)
Of manifestations of grief: Bitter, painful.
Expressing or betokening intense grief, misery, or affliction of spirit.
Of a period, place, action, etc.: characterized by sorrow, full of sorrow; (in early use esp.) hard, sore, bitter.