having a sharp, pungent taste or smell; not sweet

raw berries have an intensely bitter flavour

feeling or showing anger, hurt, or resentment because of bad experiences or a sense of unjust treatment

I don't feel jealous or bitter

she wept bitter tears of self-reproach

painful or unpleasant to accept or contemplate

today's decision has come as a bitter blow

she knew from bitter experience how treacherous such feelings could be

(of wind or weather) intensely cold

a bitter February night