depending on; according to; nature of
Formal noun used after another noun (+ の) to mean 'depending on ...' or 'the nature of ...'. Often appears in set phrases like いかんによって or いかんにかかわらず.
The result depends on your effort.
what is ...?; how is ...?; what will become of ...?
Formal sentence-ending adverb used to ask about the state or outcome of something, often with a nuance of concern or uncertainty. Common in written or rhetorical questions.
What will become of this plan?
What will become of Japan's future?
Depending on the weather, the match may be cancelled.
彼の真意やいかん。
What are his true intentions?
どう is the everyday casual word for 'how' or 'what', while 如何 is a much more formal, often literary term used mainly in set phrases.
いかに is a formal adverb meaning 'how' or 'in what way', while 如何 is typically used as a noun forming set phrases like 如何によって meaning 'depending on'.
次第 is the everyday word for 'depending on', as in 天気次第で, while 如何 is a more formal, bureaucratic alternative seen in set expressions like 如何によって.
遺憾 (いかん) means 'regret' and is pronounced identically to 如何 (いかん), but the two words are written differently and have unrelated meanings.
unfortunately; regrettably; to one's regret · what can be done about ...; ... cannot be helped
Applies to each form listed below
Standard kanji spelling for formal written contexts.
Kana spelling is common in less formal writing and when the kanji is considered difficult.
Rarely used kanji form; learners should prefer 如何.
Derived from classical Japanese. The kanji 如何 is a jukujikun (special reading) for いかん, not reflecting the individual character meanings. The exact historical derivation is uncertain.