also: そい
Only with reading しょい
Used to indicate the cause or reason for a situation, often with a negative connotation. Restricted to the reading しょい. In modern Japanese, せい (written 所為 or せい) is far more common for this meaning.
He admitted that the failure was his own doing.
I took time off work because of illness.
The match was postponed due to the weather.
Kanji spelling is rare and literary; the word is normally written in kana.
Obsolete kana form; modern Japanese uses しょい.
The kanji 所 (place) and 為 (do, cause) combine to suggest 'the place where something is done' or 'the doing of something'. The reading しょい is a Sino-Japanese on'yomi compound, while せい is a later shift from しょい. The exact historical derivation is uncertain.