Nag \Nag\, n. [OE. nagge, D. negge; akin to E. neigh.]

1. A small horse; a pony; hence, any horse.

2. A paramour; -- in contempt. [Obs.]

--Shak.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Nag \Nag\, v. t. & i. [imp. & p. p. Nagged; p. pr. & vb. n. Nagging.]

[Cf. Sw. nagga to nibble, peck, Dan. nage to gnaw, Icel. naga, gnaga, G. nagen, & E. gnaw.]

To tease in a petty way; to scold habitually; to annoy; to fret pertinaciously. [Colloq.]

``She never nagged.'' --J. Ingelow.

Source: Webster's Revised Unabridged Dictionary (1913)