See dial-up networking.

ETYM AS. dunn, of Celtic origin; cf. W. dwn, Irish and Gael. donn.
(Homonym: done).
Of a dull grayish brown to brownish gray color.

A dun horse.
Horse of a dull brownish gray color.

1. A color varying around light grayish brown; SYN. grayish brown, greyish brown, fawn.
2. A person who duns
3. An urgent request; especially; a demand for payment

1. To cure by salting.
2. To make a dun color.
3. To persistently ask for overdue payment.