1 level, horizontal, even, smooth, plane, unbroken, uninterrupted:
I looked out over the flat surface of the frozen bay.
2 prostrate, prone, supine, lying (down), stretched out, recumbent, outstretched, reclining, spread-eagle(d), spread out, outspread:
I lay flat on my back staring up at the sky.
3 collapsed, levelled, overthrown, laid low:
The air raid had left all the buildings completely flat.
4 downright, outright, unqualified, unreserved, unconditional, absolute, categorical, explicit, unconditional, definite, firm, positive, out-and-out, unequivocal, peremptory, unambiguous, unmistakable, direct, complete, total:
The request for clemency was met with the judge's flat refusal.
5 featureless, monotonous, dull, dead, uninteresting, unexciting, vapid, bland, empty, two-dimensional, insipid, boring, tiresome, lifeless, spiritless, lacklustre, prosaic, stale, tired, dry, jejune:
The critics wrote that she turned in a very flat performance.
6 deflated, collapsed, punctured, ruptured, blown out:
We had a flat tyre on the way.
7 unchangeable, unchanging, invariable, unvaried, unvarying, standard, fixed, unmodified, unmodifiable, Colloq US cookie-cutter:
They charge the same flat rate for children, the elderly, and all between.
8 dead, insipid, stale, tasteless, flavourless, unpalatable; decarbonated, non-effervescent:
9 exact, precise:
It's a flat ten minutes from here to the railway station.
10 definite, certain, sure, irrevocable:
I said I'm not going, and that's flat.
11 dull, slow, sluggish, inactive, depressed:
Business has been a bit flat since Christmas.
12 dull, mat or matt or matte, unshiny, non-gloss(y), non-reflective, non-glare, unpolished:
The table looks better with a flat finish.
13 lacking perspective, two-dimensional, lifeless, unrealistic:
Some of his paintings seem pretty flat to me.
14 Often, flats.
(a) US low shoes, loafers, sandals, Colloq flatties:
Cynthia said that wearing flats makes her feet hurt.
(b) lowland(s), plain(s), tundra, steppe(s), prairie(s), savannah or savanna, heath, moor, pampas; mud-flat(s); shallow(s), shoal, strand; marsh, bog, fen, swamp:
Before us was a large flat of barren ground.
15 rooms, suite, apartment:
How can you afford to keep a flat in London?
16 absolutely, completely, categorically, utterly, wholly, uncompromisingly, irrevocably, positively, definitely, directly; exactly, precisely, flatly:
He has come out flat in favour of the status quo. When he started drinking, she left him flat.
17 flat out.
(a) at maximum or top or full or breakneck speed, speedily, quickly, apace, on the run, rapidly, swiftly, at full speed or gallop, post-haste, hell for leather, like a bat out of hell, like a shot, like (greased) lightning, like the wind:
Someone shouted 'Fire!' and we headed flat out for the exits.
(b) flatly, unhesitatingly, directly, at once, immediately, forthwith, without delay; plainly, openly, baldly, brazenly, brashly:
He asked to borrow some money and she told him 'No', flat out.
18 room(s), flat, suite (of rooms), chambers, tenement; garden flat, maisonette, penthouse, studio, Brit bedsitter, bedsit; accommodation, living quarters, Colloq Brit digs, US and Canadian apartment, furnished room, walk-up, duplex, triplex, garden apartment:
We rented a two-bedroom flat in a good neighbourhood.