Used to state the reason or cause for something, often in formal or written contexts. Frequently appears in the pattern ～が故に or ～故の.
貧しさ故に、彼は進学を諦めた。
Because of poverty, he gave up on going to higher education.
because of; as a result of
Conjunctive use, equivalent to ～のために or ～の理由で. Attaches to nouns or nominalized phrases, often in the form ～故（に）.
事故故に電車が遅れた。
The train was delayed because of an accident.
This is a mistake that comes from youthful inexperience.
It was a failure due to lack of experience.
彼は若さ故に過ちを犯した。
He made a mistake because of his youth.
病気ゆえ、会議には出席できません。
Due to illness, I will not be able to attend the meeting.
理由 is the common, everyday word for 'reason', while 故 is a formal, literary term used mainly in written or elevated speech.
為 is the standard, neutral way to say 'because of' or 'for the sake of', while 故 gives the same meaning a more formal, almost archaic feel.
訳 is a casual, conversational word for the reason or circumstances behind something, whereas 故 belongs to formal or literary registers.
Kanji form; usually written in kana.
Kana spelling is the most common and recommended for general use.
Derived from classical Japanese, where 故 (yue) meant 'reason' or 'cause'. The kanji 故 carries the meaning of 'reason' or 'circumstances'.