tapper

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One that taps.

from The Century Dictionary.

• noun A hammer for striking a bell or chime.
• noun A device for restoring a coherer to its normal resistance, after this has been affected by electric oscillations, by means of a series of slight mechanical shocks.
• noun One who or that which taps or strikes.
• noun One who taps or draws liquor; a tapster; specifically, an innkeeper.
• noun One who or that which operates a screw-cutting tap for threading holes.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.), Prov. Eng. The lesser spotted woodpecker (Dendrocopus minor); -- called also tapperer, tabberer, little wood pie, barred woodpecker, wood tapper, hickwall, and pump borer.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One who taps
• noun A tap-dancer
• noun A phone tapper or wiretapper
• noun US A tapster
• noun telegraphy In early wireless telegraphs, a device used to shake loose the filings of a coherer.
• noun UK, dialect The lesser spotted woodpecker.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who wiretaps a telephone or telegraph wire
• noun a dancer who sounds out rhythms by using metal taps on the toes and heels of the shoes
• noun a tavern keeper who taps kegs or casks
• noun a person who strikes a surface lightly and usually repeatedly
• noun a worker who uses a tap to cut screw threads