From Old Japanese. Cognate with 憎む (nikumu, “to hate”), 難い (-nikui, “difficult [to do]”, verb suffix).
憎い (-i inflection, hiragana にくい, rōmaji nikui)
- hateful, detestable, abominable
- Ise Monogatari (The Tales of Ise), late 800s to early 900s:
- Saredo nikuku hata arazarikeri.
- But no one thought him dislikeable.
- → Note that the negative connotations have strengthened over time. The older meaning was milder, closer to dislikeable than the modern hateful.