noun, noun which may take the genitive case particle 'no'
single-seater; single-seated
Describes vehicles, aircraft, or seats designed for one person. Often used as a noun or with の to modify another noun.
この飛行機は単座の戦闘機です。
This aircraft is a single-seat fighter.
単座の車両は軽量で燃費が良い。
Single-seater vehicles are lightweight and fuel-efficient.
noun
sitting alone
Refers to the act of sitting by oneself, not necessarily in a vehicle. Less common than sense 1; often used in descriptive or literary contexts.
彼は公園のベンチで単座していた。
He was sitting alone on a park bench.
Compound of 単 (single) and 座 (seat). The kanji 座 is commonly used for seating, while the variant 坐 is an older form.