I. ˈ ̷ ̷| ̷ ̷ noun
Etymology: reduplication of tap (V)
: a series of taps or their sound
steady tap-tap of typewriters — Manchester Guardian Weekly
II. intransitive verb
: to make a sound of repeated tapping : move with a sound of tapping
her shoes were tap-tapping on the tessellated floor — W.G.Hardy
dark plane-tree leaves tap-tapped at the window — John Galsworthy