noun
Only when written 相方
Especially common in manzai comedy for the straight man or partner, but can refer to any close companion or counterpart.
See also: 漫才
彼は漫才の相方を探している。
He is looking for a manzai partner.
仕事の相方と一緒にプロジェクト
I worked on the project together with my work partner.
noun
partner for the night
Historical or euphemistic term for a companion chosen at a brothel or entertainment district; not used in modern everyday conversation.
江戸時代の遊郭では、客は相方を選んだ。
In Edo-period pleasure quarters, customers chose a partner for the night.
相棒 is a more common and general word for a partner or buddy, often used in police or work contexts, while 相方 is strongly associated with manzai duos.
Compound of 相 (mutual) and 方 (person/direction), literally 'the other party'. The reading あいかた is a kun'yomi compound.