adverb
Etymology: Middle English (Scots), from Middle English flat (I) + -ly
1. obsolete : into a flat position : prostrate
2.
a. : bluntly , categorically , plainly
he flatly denied the charges
sometimes : emphatically , peremptorily
presenting the case flatly and sternly
flatly challenged the truth of the statement
b. : absolutely , wholly
acting flatly against his convictions
3. : in a flat manner
sagging flatly in his arms
as
a. : without zest or spirit : in a dull and uninterested manner
droned on flatly about her troubles
b. : without indication or development of a third dimension
roses stenciled flatly on the chair backs