na-adjective
Describes surfaces, shapes, or abstract things that are flat, even, or without variation. Used as a な-adjective.
この道はフラットで走りやすい。
This road is flat and easy to run on.
料金はフラットなので、使い放題だ。
The fee is flat, so it's unlimited use.
noun
Used after a time expression to mean 'exactly' or 'in just', as in '10 seconds flat'. Noun usage.
彼は100メートルを10秒フラットで走った。
He ran 100 meters in 10 seconds flat.
noun
Musical term for a note lowered by a semitone. Compare with シャープ (sharp).
See also: シャープ
この曲はフラットが多くて難しい。
This piece has many flats and is difficult.
noun
Loanword for an apartment or flat, especially in a Western context. Less common than アパート or マンション in everyday Japanese.
ロンドンでフラットを借りるのは高い。
Renting a flat in London is expensive.