harp

Concise Oxford English Dictionary © 2008 Oxford University Press:
harp/hɑːp/

▶noun a musical instrument, roughly triangular in shape, consisting of a frame supporting a graduated series of parallel strings, played by plucking with the fingers. ▶verb

• 1 (harp on) talk or write persistently and tediously on (a topic).

• 2 archaic play on a harp.

– derivatives
harper noun,
harpist noun.

– origin OE hearpe, of Gmc origin.