締める
しめる · shimeru · JLPT N5 · verb-ichidan
to tighten
👔 shimeru: she-MAY-rue a loose knot, so tighten it
締 = thread radical 糸 + 帝 (tei, the sound part): thread pulled tight. Used for ties, belts, seatbelts: ネクタイを締める = to fasten a necktie. Same reading as 閉める (to close) — both mean bringing something shut or snug.