Carrier

1. One who, or that which, carries or conveys; a messenger.
2. One who is employed, or makes it his business, to carry goods for others for hire; a porter; a teamster.
3. (Mach.) That which drives or carries; as: (a) A piece which communicates to an object in a lathe the motion of the face plate; a lathe dog. (b) A spool holder or bobbin holder in a braiding machine. (c) A movable piece in magazine guns which transfers the cartridge to a position from which it can be thrust into the barrel.
Carrier pigeon (Zoöl.),
a variety of the domestic pigeon used to convey letters from a distant point to to its home.
Carrier shell (Zoöl.),
a univalve shell of the genus Phorus; -- so called because it fastens bits of stones and broken shells to its own shell, to such an extent as almost to conceal it.
Common carrier (Law.)
See under Common, a.