noun
A threaded fastener; also used metaphorically for something that tightens or adjusts.
このネジを時計回りに回してください。
Please turn this screw clockwise.
ネジが緩んでいたので、ドライバーで締めた。
The screw was loose, so I tightened it with a screwdriver.
noun
key (of a clock, watch, etc.); spring
Refers to the winding key or the mainspring of a mechanical clock or watch; often in compound words like ネジ巻き (winding).
古い時計のネジを巻くのを忘れないで。
Don't forget to wind the old clock.
このオルゴールはネジを巻くと音が鳴る。
This music box plays when you wind it up.
Rare kanji form; 螺 means 'spiral' and 子 is a nominalizer, but this spelling is seldom used.
Rare kanji form; 捩 also means 'twist' or 'wrench'.
Rare kanji form; 捻 means 'twist', reflecting the twisting motion of a screw.
Rare kanji form; 螺旋 normally reads らせん (spiral), but can be used as ateji for ねじ.
The word ねじ likely derives from the verb 捩る (ねじる, 'to twist'), referring to the twisting motion of a screw. The katakana spelling ネジ is standard in modern usage.