1. A small pin, or cylinder, formerly of bone, now most commonly of wood, used in the making of pillow lace. Each thread is wound on a separate bobbin which hangs down holding the thread at a slight tension.
2. A spool or reel of various material and construction, with a head at one or both ends, and sometimes with a hole bored through its length by which it may be placed on a spindle or pivot. It is used to hold yarn or thread, as in spinning or warping machines, looms, sewing machines, etc.
5. (Science: physics) a cylindrical or spool-shaped coil or insulated wire, usually containing a core of soft iron which becomes magnetic when the wire is traversed by an electrical current. Bobbin and fly frame, a roving machine. Bobbin lace, lace made on a pillow with bobbins; pillow lace.