tapper

Short definition from Wiktionary

Noun

1. 1
   One who makes a tapping noise.
2. 2
   A tap-dancer.
3. 3
   A wiretapper.
4. 4
   A weakly hit ground ball.
5. 5
   In early wireless telegraphs, a device used to shake loose the filings of a coherer.
6. 6
   The lesser spotted woodpecker.
7. 7
   A tapster.
8. 8
   An assistant in the sport of paraswimming who taps blind or visually impaired swimmers with a pole to indicate when they should turn around.

Proper noun

1. 1
   A surname originating as an occupation for an innkeeper or wine merchant.