n. 25B6; adjective
a flat surface : LEVEL, horizontal; smooth, even, uniform, regular, plane.
the sea was flat : CALM, still, pacific, glassy, undisturbed, without waves, like a millpond.
a flat wooden box : SHALLOW, low-sided.
flat sandals : LOW, low-heeled, without heels.
his voice was flat : MONOTONOUS, toneless, droning, boring, dull, tedious, uninteresting, unexciting, soporific; bland, dreary, colourless, featureless, emotionless, expressionless, lifeless, spiritless, lacklustre.
he felt flat and weary : DEPRESSED, dejected, dispirited, despondent, downhearted, disheartened, low, low-spirited, down, unhappy, blue; without energy, enervated, sapped, weary, tired out, worn out, exhausted, drained; informal down in the mouth/dumps.
the market was flat : SLOW, inactive, sluggish, slack, quiet, depressed.
(Brit.) a flat battery : EXPIRED, dead, finished, used up, run out.
a flat tyre : DEFLATED, punctured, burst.
a flat fee : FIXED, set, regular, unchanging, unvarying, invariable.
a flat denial : OUTRIGHT, direct, absolute, definite, positive, straight, plain, explicit; firm, resolute, adamant, assertive, emphatic, categorical, unconditional, unqualified, unequivocal.
vertical, uneven.
25B6; adverb
she lay down flat on the floor : STRETCHED OUT, outstretched, spreadeagled, sprawling, prone, supine, prostrate, recumbent.
(informal) she turned me down flat : OUTRIGHT, absolutely, firmly, resolutely, adamantly, emphatically, insistently, categorically, unconditionally, unequivocally.
25A0; flat out HARD, as hard as possible, for all one's worth, to the full/limit, all out; at full speed, as fast as possible, at full tilt; informal like crazy, like mad, like the wind, like a bomb; Brit. informal like billy-o, like the clappers.