Possible Definitions:
1. Flat (superl.) Having an even and horizontal surface, or nearly so, without prominences or depressions; level without inclination; plane.
2. Flat (superl.) Lying at full length, or spread out, upon the ground; level with the ground or earth; prostrate; as, to lie flat on the ground; hence, fallen; laid low; ruined; destroyed.
3. Flat (superl.) Wanting relief; destitute of variety; without points of prominence and striking interest.
4. Flat (superl.) Tasteless; stale; vapid; insipid; dead; as, fruit or drink flat to the taste.
5. Flat (superl.) Unanimated; dull; uninteresting; without point or spirit; monotonous; as, a flat speech or composition.
6. Flat (superl.) Lacking liveliness of commercial exchange and dealings; depressed; dull; as, the market is flat.
7. Flat (superl.) Clear; unmistakable; peremptory; absolute; positive; downright.
8. Flat (superl.) Below the true pitch; hence, as applied to intervals, minor, or lower by a half step; as, a flat seventh; A flat.
9. Flat (superl.) Not sharp or shrill; not acute; as, a flat sound.
10. Flat (superl.) Sonant; vocal; -- applied to any one of the sonant or vocal consonants, as distinguished from a nonsonant (or sharp) consonant.
11. Flat (adv.) In a flat manner; directly; flatly.
12. Flat (adv.) Without allowance for accrued interest.
13. Flat (n.) A level surface, without elevation, relief, or prominences; an extended plain; specifically, in the United States, a level tract along the along the banks of a river; as, the Mohawk Flats.
14. Flat (n.) A level tract lying at little depth below the surface of water, or alternately covered and left bare by the tide; a shoal; a shallow; a strand.
15. Flat (n.) Something broad and flat in form
16. Flat (n.) A flat-bottomed boat, without keel, and of small draught.
17. Flat (n.) A straw hat, broad-brimmed and low-crowned.
18. Flat (n.) A car without a roof, the body of which is a platform without sides; a platform car.
19. Flat (n.) A platform on wheel, upon which emblematic designs, etc., are carried in processions.
20. Flat (n.) The flat part, or side, of anything; as, the broad side of a blade, as distinguished from its edge.
21. Flat (n.) A floor, loft, or story in a building; especially, a floor of a house, which forms a complete residence in itself.
22. Flat (n.) A horizontal vein or ore deposit auxiliary to a main vein; also, any horizontal portion of a vein not elsewhere horizontal.
23. Flat (n.) A dull fellow; a simpleton; a numskull.
24. Flat (n.) A character [/] before a note, indicating a tone which is a half step or semitone lower.
25. Flat (n.) A homaloid space or extension.
26. Flat (v. t.) To make flat; to flatten; to level.
27. Flat (v. t.) To render dull, insipid, or spiritless; to depress.
28. Flat (v. t.) To depress in tone, as a musical note; especially, to lower in pitch by half a tone.
29. Flat (v. i.) To become flat, or flattened; to sink or fall to an even surface.
30. Flat (v. i.) To fall form the pitch.
31. Flat (a.) Having a head at a very obtuse angle to the shaft; -- said of a club.
32. Flat (a.) Not having an inflectional ending or sign, as a noun used as an adjective, or an adjective as an adverb, without the addition of a formative suffix, or an infinitive without the sign to. Many flat adverbs, as in run fast, buy cheap, are from AS. adverbs in -e, the loss of this ending having made them like the adjectives. Some having forms in ly, such as exceeding, wonderful, true, are now archaic.
33. Flat (a.) Flattening at the ends; -- said of certain fruits.
