不可解|ふかかいfukakai[2]nakadaka (mid-high)

1. na-adjective, nounincomprehensible; mysterious; inexplicable; inscrutable; enigmatic; baffling
   愛あいの動うごきは不可解ふかかい。↗

   Love moves in mysterious ways.

• Synonym不思議ふしぎNeutralWonderful, marvelous, mysterious — the everyday default in speech, often with a note of wonder; 「不可解」 stresses what you can't grasp rationally.
• Synonym不可思議ふかしぎWrittenWritten/formal prose: beyond human understanding; also for things that are simply hard to grasp. Stronger than 「不思議」.
• SynonymミステリアスNeutralLoanword for mysterious with a positive, alluring shade, as in 「ミステリアスな女性」.
• Synonym謎なぞNeutralA riddle or mystery, as in 「謎の多い事件」; a noun, leaning toward the mysterious.
• Synonym難解なんかいNeutralHard to understand; said mostly of books and theories, as in 「難解な本」.
• Synonym神秘しんぴNeutralMystery with a sense of awe, as in 「自然の神秘」.
• SynonymミステリーNeutralLoanword: a mystery, or a mystery novel, as in 「ミステリー小説」.
• Synonym訳が分からないわけがわからないCasualColloquial: baffling, makes no sense. Can simply mean you don't get it, or carry a tone of annoyance.
• Synonym晦渋かいじゅうWrittenWritten/formal prose: dense, hard-to-follow writing, as in 「晦渋な文章」.
• Related不明ふめいNeutralUnclear or unknown, as in 「原因不明」; leans toward missing information rather than puzzlement.
• Related曖昧あいまいNeutralVague or ambiguous, as in 「曖昧な返事」; leans toward evasive attitudes.
• Related怪かいWrittenWritten/formal prose for the strange and eerie; mostly in set phrases like 「怪を語る」; rare.
• Related怪奇かいきNeutralBizarre and eerie, as in 「怪奇現象」; carries a horror tinge.
• Related不明瞭ふめいりょうWrittenWritten/formal prose: unclear or indistinct, as in 「不明瞭な説明」; leans toward unclear expression.
• Related曖昧模糊あいまいもこWrittenFour-character compound for hazy, ill-defined things; an emphatic written/formal variant.
• Related不分明ふぶんめいWrittenWritten/formal prose: indistinct; rare. Close to 「不明瞭」.
• Related未解明みかいめいWrittenWritten/formal prose: not yet explained or solved, as in 「未解明の謎」; leans scientific.
• Related鵺的ぬえてきWrittenWritten/formal prose: of unknown identity or an ambiguous stance; rare.
• Related幻怪げんかいWrittenWritten/formal prose: eerie and unsettling; very rare.
• Related隠微いんびWrittenWritten/formal prose: hidden and hard to make out, as in 「隠微な心理」.
• Related怪事かいじWrittenWritten/formal prose: a strange affair; rare; leans toward bizarre incidents.
• Antonym明快めいかいNeutralAntonym: clear and well-organized — the opposite of 「不可解」's incomprehensibility.
• Antonym明白めいはくNeutralAntonym: obvious and beyond doubt, as in 「明白な事実」 — the opposite of 「不可解」.

Use 「不可解」 for something you can't make sense of no matter how you think about it, as in 「不可解な行動」「不可解な事件」. For everyday wonder or strangeness, 「不思議」 is the usual word in speech; 「訳が分からない」 covers baffling, make-no-sense situations colloquially. 「難解」 suits hard books and theories, 「謎」 names a mystery, 「不明」 an unknown cause, and 「ミステリアス」 a positive, mysterious air. For the opposite — clear and lucid — pick 「明快」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 理解りかい・解決かいけつできない様子ようす。