Meaning of screw-on

screw-on

Pronunciation: (skr'on", -ôn"), [key]
— adj.
  1. attached, connected, or closed by screwing onto another part of a container or receptacle.
  2. (of an earring) held on the earlobe by a small screwlike post with a disk at the tip.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.