Synonyms For "Bitter" :

2 syllables:

acerb, acid, acrid, biting, caustic, hostile

3 syllables:

acerbic, bitingly, bitterly, bitterness, blistering, piercingly, resentful, sorrowful, sulfurous, sulphurous, unpleasant, virulent

4 syllables:

unbearable, vitriolic

5 syllables:

acrimonious, intolerable

6 syllables:

unendurable