flat

In a horizontal line or plane; not sloping.

Smooth; having no protrusions, indentations or other surface irregularities, or relatively so.

(slang) Having small or invisible breasts and/or buttocks.

At a consistently depressed level; consistently lacklustre.

(not comparable, commerce) Of fees, fares etc., fixed; unvarying.

(music, voice) Without variations in pitch.

(of colours) Without variation in tone or hue; uniform.

(figuratively) Lacking liveliness or action; depressed; uninteresting; dull and boring.

(authorship, figuratively, especially of a character) Lacking in depth, substance, or believability; underdeveloped; one-dimensional.

(music, note) Lowered by one semitone.

(music) Of a note or voice, lower in pitch than it should be.

Absolute; downright; peremptory.

(of a tire or other inflated object) Deflated, especially because of a puncture.

(of a carbonated drink) With all or most of its carbon dioxide having come out of solution so that the drink no longer fizzes or contains any bubbles.

(wine) Lacking acidity without being sweet.

(of a battery) Unable to emit power; dead.

(juggling, of a throw) Without spin; spinless.

(phonetics, dated, of a consonant) Sonant; vocal, as distinguished from a sharp (non-sonant) consonant.

(grammar) Not having an inflectional ending or sign, such 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".

(golf, of a golf club) Having a head at a very obtuse angle to the shaft.

(horticulture, of certain fruits) Flattening at the ends.

(of measurements of time) Exact.