bitterness(quality of being bitter in taste) noun [UK: ˈbɪ.tə.nəs] [US: ˈbɪ.tər.nəs]He couldn't stand the bitterness of the coffee. = No podía soportar el amargor del café.
wormwood(that which causes bitterness) noun [UK: ˈwɜːm.wʊd] [US: ˈwɜːrˌm.wʊd]