nag

Concise Oxford English Dictionary © 2008 Oxford University Press:
nag1

▶verb (nags, nagging, nagged)

• 1 constantly ask (someone) to do something which they are reluctant to do.

• 2 (often as adj. nagging) be persistently painful or worrying to.

▶noun

• 1 a person who nags.

• 2 a persistent feeling of anxiety: he felt a little nag of doubt.

– derivatives
nagger noun,
naggingly adverb,
naggy adjective.

– origin C19 (orig. dial. in the sense ‘gnaw’): perh. of Scand. or Low Ger. origin.

Concise Oxford English Dictionary © 2008 Oxford University Press:
nag2

▶noun informal, often derogatory a horse, especially one that is old or in poor health.

■ archaic a horse suitable for riding rather than as a draught animal.

– origin ME: of unknown origin.