理由 is the everyday word for 'reason' usable in any context, while 事由 is a stiff, formal term mainly found in official documents and legal text.
理由 is the plain, common word for 'reason,' whereas 次第 is a stiffer, more formal noun used in explanatory phrases.
理由 is a neutral word for 'reason', while 言い訳 specifically implies an excuse offered to avoid blame.
理由 is the common, everyday word for 'reason', while 故 is a formal, literary term used mainly in written or elevated speech.
理由 is the everyday word for a reason, while 由 is a more formal, literary term that can imply a deeper or reported cause.
理由 means 'reason' as a standalone noun, whereas ため links a cause to its result within a sentence, as in 〜のため.
理由 is the common, everyday word for 'reason' or 'cause', while 論拠 is a more formal term stressing the logical support behind a position in an argument.
理由 usually points to a single, specific reason, while 諸事情 vaguely covers several unspecified reasons at once.
理由 is a direct cause or reason for something, whereas 事情 covers the broader set of circumstances that may include several reasons.
理由 is a neutral word for 'reason' that may be entirely genuine, whereas 口実 implies the stated reason is convenient or possibly not the real one.
理由 is the concrete cause or reason behind a specific event, whereas 道理 is the abstract principle of reason or moral rightness.
理由 is a concrete reason or cause for a specific event, while 理 is the abstract principle or logic behind things in general.
理由 is a neutral reason or cause for something, while 理屈 implies a whole chain of logic, sometimes with a negative connotation of being overly argumentative.
