What does "vibrator" mean?

Vibrator: (a) (Elec.) (1) A trembler, as of an electric bell. (2) A vibrating reed for transmitting or receiving pulsating currents in a harmonic telegraph system. (3) A device for vibrating the pen of a siphon recorder to diminish frictional resistance on the paper. (4) An oscillator. (b) An ink-distributing roller in a printing machine, having an additional vibratory motion. (a) (Music) A vibrating reed, esp. in a reed organ. (d) (Weaving) Any of various vibrating devices, as one for slackening the warp as a shed opens. (e) An attachment, usually pneumatic, in a molding machine to shake the pattern loose.