adjectival noun or quasi-adjective, noun

  1. indispensable, essential.

Variations

Pronunciation Kanji Kana Is Common
不可欠 ふかけつ

Contained Kanji Breakdown

negative, non-, bad
 (4th, N4)
cliff (厂) variant
divining, fortune-telling, divination or katakana to radical (no. 25)
ボク うらな.う うらない (Kentei Pre-1)
can, passable, mustn't
カ コク -べ.き (5th)
street, ward, town
チョウ テイ チン (3rd, N1)
mouth
くち コウ ク (1st, N4)
lack, gap, fail
ケツ か.ける ケン (4th, N3)
knife, wrapping enclosure(勹) variant
person
ひと ニン ジン (1st, N5)