憎い
にくい · nikui · JLPT N2 · i-adj
hateful
憎 = hate (root of 憎む, to hate) + い adjective ending = hateful
The kanji 憎 is the 'hate' root, seen in the verb 憎む (nikumu, to hate). Adding the i-adjective ending い turns it into a descriptive word meaning hateful or detestable.