苦しむ
くるしむ · kurushimu · JLPT N3 · verb-godan
to suffer
💊 苦 = bitter (as in 苦い nigai); kurushimu: crew-shh-moo, groaning from it
The kanji 苦 means bitter, so to suffer is to taste something bitter. 苦 is grass 艹 over old 古: old herbs turn bitter. The adjective 苦しい kurushii means painful, and the verb 苦しむ kurushimu means to go through that pain.
苦 — grass radical 艹 + 古 (old)
Originally referred to a bitter-tasting plant, with the grass radical 艹 indicating its botanical nature and 古 providing the phonetic element. The meaning extended from the literal bitter taste to figurative senses of hardship, suffering, and painful effort.