欠 （ケツ） lack, deficiency, vacancy, absence, non-attendance

欠缺 （ケンケツ） lacuna, gap where something is lacked

法の欠缺 （ホウノケンケツ） gap in the law

欠ける （かける） to chip, to be chipped, to break (off), to be damaged, to be missing (from a set, team, etc.), to be absent, to become lost, to be lacking (in), to be short (of), to be deficient, to be wanting (in), to wane (of the moon), to go into eclipse