dun

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To importune (a debtor) for payment: a dunning letter.
2. n. One that duns.
3. n. An importunate demand for payment.
4. n. An almost neutral brownish gray to dull grayish brown.
5. n. A fishing fly having this color.
6. n. A horse of this color.

Century Dictionary and Cyclopedia

1. Of a color partaking of brown and black; of a dull-brown color; swarthy.
2. Dark; gloomy.
3. n. A familiar name for an old horse or jade: used as a quasi-proper name (like dobbin).
4. To make of a dun or dull-brown color.
5. Especially To cure, as cod, in such a manner as to impart a dun or brown color. See dunfish.
6. To become of a dun color.
7. To make a loud noise; din.
8. To demand payment of a debt from; press or urge for payment or for fulfilment of an obligation of any kind.
9. n. One who duns; an importunate creditor, or an agent employed to collect debts.
10. n. A demand for the payment of a debt, especially a written one; a dunning-letter: as, to send one's debtor a dun.
11. n. A hill; a mound; a fortified eminence. This word enters into the composition of many place-names in Great Britain, frequently under the modifled forms dum-, don-, -don (as well as down, which see): as, Dunstable, Dunmow, Dundee, Dunbar, Dumfries, Dumbarton, Doncaster, Donegal, etc.
12. n. A dun-colored natural or artificial fly used in angling: as, the pale-olive dun, made with a body of hair from the polar bear; goose-dun, with a body of gray goose-pinion; blue dun, with a body of pale mole-fur.

Wiktionary

1. n. uncountable A brownish grey colour.
2. adj. Of a brownish grey colour.
3. n. countable A collector of debts.
4. v. transitive To ask or beset a debtor for payment.
5. v. transitive To harass by continually repeating e.g. a request.
6. n. A valley in the Himalayan foothills, e.g. Dehra Dun.
7. n. countable A newly hatched, immature mayfly.
8. v. informal Eye dialect spelling of done: simple past tense and past participle of do.
9. Eye dialect spelling of don't.

GNU Webster's 1913

1. n. A mound or small hill.
2. v. To cure, as codfish, in a particular manner, by laying them, after salting, in a pile in a dark place, covered with salt grass or some like substance.
3. v. To ask or beset (e.g., a debtor), for payment; to urge importunately.
4. n. One who duns; a dunner.
5. n. An urgent request or demand of payment.
6. adj. Of a dark color; of a color partaking of a brown and black; of a dull brown color; swarthy.

WordNet 3.0

1. v. treat cruelly
2. v. cure by salting
3. v. make a dun color
4. n. horse of a dull brownish grey color
5. adj. of a dull greyish brown to brownish grey color
6. n. a color or pigment varying around a light grey-brown color
7. v. persistently ask for overdue payment