How to say "knock" in Japanese

• 打つうつJLPT N4approx.Common
  godan verb, transitive verbCovers striking or hitting something generally, and can express knocking by striking a surface. For a door, though, the loanword is usually what you want.
  階段かいだんから落おちて背中せなかを強つよく打うちました。↗

  I fell down the stairs and hit my back very hard.
• ノックJLPT N3approx.Common
  noun, suru verb, transitive verbThe katakana noun for knocking, especially on a door. This is the default word when you mean knocking at a door before entering.
  誰だれかがドアをノックした。↗

  Someone knocked on the door.
• ぶつけるJLPT N2approx.Common
  ichidan verb, transitive verbMainly means to bump or run one thing into another, such as hitting one's head. Its gloss 'to knock' reflects this bumping sense, so it is seldom the word for knocking on a door.
  彼かれは頭あたまを棚たなに強つよくぶつけて大おおきなこぶを作つくった。↗

  He banged his head against a shelf and got a big lump.
• 叩くたたくJLPT N3approx.Common
  godan verb, transitive verbMeans to strike, hit, or beat, including knocking on a door or surface with the hand or knuckles. A natural choice when the physical tapping action itself is in focus.
  見知みしらぬ人ひとが玄関げんかんのドアをしきりにたたいた。↗

  A stranger beat urgently at the front door.

For a door, 「ノック」 is the natural choice; 「叩く」 or 「打つ」 work for striking by hand, while 「ぶつける」 is really about bumping or running one thing into another, not knocking on doors.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 打つうつto hit
• ノックknock
• ぶつけるto hit (e.g. one's head)
• 叩くたたくto strike
• とんtap
• ぶっつけるto hit (e.g. one's head)
• 打ち付けるうちつけるto bang (e.g. one's head)