つらい・辛いtsurai[2]nakadaka (mid-high)

1. i-adjectivepainful; bitter; heart-breaking; difficult (emotionally)
2. i-adjectivetough; difficult; hard (usu. of situations)
3. i-adjectivecruel; harsh; cold

• Synonym苦しいくるしいNeutralDistress of any kind — breathlessness, mental anguish, money troubles (「生活が苦しい」); often interchangeable with 「辛い」, but originally a suffocating, tight-chested feeling.
• SynonymきついCasualColloquial for tiring, strenuous work or something tight (「仕事がきつい」「服がきつい」); the emphasis is on a heavy burden.
• Synonym切ないせつないNeutralHeart-wrenching, wistful sorrow (「切ない恋」) with a lyrical tinge; 「辛い」 stresses suffering that is hard to endure.
• SynonymしんどいCasualColloquial, with a Kansai flavour: tired, drained, a real effort (「今日はしんどい」); mostly about physical exhaustion.
• Related痛いいたいNeutralRefers to physical or mental pain (「頭が痛い」), focusing on the pain itself; 「辛い」 is about unbearable emotional distress or a hard situation.
• Related悲しいかなしいNeutralSad or sorrowful; the emphasis is on grief, while 「辛い」 is about painful distress that need not involve sadness.
• Related心苦しいこころぐるしいWrittenWritten/formal: feeling you have put someone out, a guilty unease (「お手数をおかけして心苦しい」); mostly for apologising to someone.
• Related大変たいへんNeutralSomething serious, awful or a huge effort (「大変だね」); very common in speech and more objective than 「辛い」.
• Related厳しいきびしいNeutralStrict, severe, or harsh conditions (「厳しい状況」); the emphasis is on harsh outside circumstances rather than one's own feelings.
• Related悲痛ひつうWrittenWritten/formal: extreme grief (「悲痛な叫び」), strongly literary and centred on sorrow; 「辛い」 covers any unbearable suffering, not just sadness.

Use 「辛い」 for emotional or situational hardship that is hard to bear. For physical pain say 「痛い」; for tiring, strenuous things 「きつい」 or 「しんどい」; for sadness 「悲しい」; for wistful heartache 「切ない」. 「苦しい」 often swaps in for 「辛い」.

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

1. くるしい。苦痛くつうである。心身しんしんに沁しみるような痛いたさ。
2. 相手あいてにつらさを与あたえるような行為こうい。