無効(むこう)

むこう
noun / na-adjective
invalid, void, null
See also: 向(む)こう (over there), 向こう(むこう) (over there)
1. invalid, void, null and void
Having no legal force or effect; not valid. Used for contracts, tickets, votes, and other items that are no longer enforceable or usable.
この切符(きっぷ)は無効(むこう)です。
This ticket is invalid.
契約(けいやく)が無効(むこう)になった。
The contract became void.
記入(きにゅう)ミスがあった場合(ばあい)、その投票(とうひょう)用紙(ようし)は無効(むこう)扱(あつか)いとなります。
If there is a filling error, that ballot will be treated as invalid.

WORD FORMATION:
無(む) (without, none) + 効(こう) (effect, validity)

USAGE:
Used in legal, administrative, and technical contexts for things that have no force or effect. Functions as a noun or na-adjective.

COMMON COLLOCATIONS:

  • 無効(むこう)になる: to become invalid
  • 無効(むこう)にする: to invalidate, to void
  • 無効(むこう)投票(とうひょう): invalid vote, spoiled ballot
  • 契約(けいやく)無効(むこう): contract nullification
  • 無効(むこう)扱(あつか)い: treated as invalid

CONTRAST:

  • 無効(むこう): invalid, void (no legal/practical effect)
  • 有効(ゆうこう): valid, effective (the antonym)

CAUTION:
Do not confuse with the homophone 向(む)こう (over there, the other side).

Related Words

Antonym: 有効(ゆうこう) (valid, effective)
Homophone: 向(む)こう (over there)
general
Added 2026.2.24 20:09 · Revised 2026.3.30 15:07
13000/13385_mukou