Etymology: Middle English, from Old Norse flatr; akin to Old High German flaz flat, and probably to Greek platys broad — more at place
Date: 14th century
a. lying at full length or spread out upon the ground ; prostrate
b. utterly ruined or destroyed
c. resting with a surface against something
a. having a continuous horizontal surface
b. being or characterized by a horizontal line or tracing without peaks or depressions <a flat EEG> 3. having a relatively smooth or even surface 4. arranged or laid out so as to be level or even 5. a. having the major surfaces essentially parallel and distinctly greater than the minor surfaces <a flat piece of wood> b. of a shoe heel very low and broad 6. a. clearly unmistakable ; downright <a flat denial> b. (1) not varying ; fixed <a flat rate> (2) having no fraction either lacking or in excess ; exact <in a flat 10 seconds> (3) of a frequency response not varying significantly throughout its range 7. a. lacking in animation, zest, or vigor ; dull <life seemed flat without her> b. lacking flavor ; tasteless c. lacking effervescence or sparkle <flat ginger ale> d. commercially inactive; also characterized by no significant rise or decline from one period to another <sales were flat> e. of a tire lacking air ; deflated f. chiefly British, of a battery dead 3c, discharged 8. a. (1) of a tone lowered a half step in pitch (2) lower than the proper pitch b. of the vowel a pronounced as in bad or bat 9. a. having a low trajectory b. of a tennis stroke made so as to give little or no spin to the ball 10. of a sail taut 11. a. uniform in hue or shade b. having little or no illusion of depth c. of a photograph or negative lacking contrast d. of lighting conditions lacking shadows or contours e. free from gloss <a flat paint> f. two-dimensional 3 <flat characters> 12. of, relating to, or used in competition on the flat <a flat horse> 13. of a universe having a mass such that expansion halts only after infinite time and collapse never occurs Synonyms: see level, insipid • flatly adverb • flatness noun • flattish adjective II. noun Date: 14th century 1. a. a level surface of land — usually used in plural <sagebrush flats> <tidal flats> b. a stretch of land without obstacles; especially a track or course for a flat race — usually used with the <has won twice on the flat> 2. a flat part or surface <the flat of one's hand> 3. a. a musical note or tone one half step lower than a specified note or tone b. a character ♭ on a line or space of the musical staff indicating a half step drop in pitch 4. something flat: as a. a shallow container for shipping produce b. a shallow box in which seedlings are started c. a flat piece of theatrical scenery d. a shoe or slipper having a flat heel or no heel 5. chiefly British an apartment on one floor 6. a deflated tire 7. the area to either side of an offensive football formation III. adverb Date: 1531 1. in a flat manner ; directly, positively 2. in a complete manner ; absolutely <flat broke> 3. below the proper musical pitch 4. without interest charge; especially without allowance or charge for accrued interest <bonds sold flat> IV. verb (flatted; flatting) Date: circa 1604 transitive verb 1. flatten 2. to lower in pitch especially by a half step intransitive verb to sing or play below the true pitch
New Collegiate Dictionary. 2001.