Several parts combine into one character.

悲 is a compound ideograph: 非 (not / contradiction) over 心 (heart). The composite captures a striking East Asian definition of sadness — sorrow is not absence or emptiness, but the heart actively crying "no!" against reality. The mind protests against what is, and that protest itself is grief. The character bundles refusal, rejection, and lament into one feeling.

Korean reading "bi." 悲劇 (bigeuk, tragedy), 悲鳴 (bimyeong, scream / cry of distress), 悲哀 (biae, sorrow), 慈悲 (jabi, mercy / Buddhist compassion). The Buddhist compound 慈悲 deserves note — it pairs 慈 (loving-kindness) with 悲 (compassionate sorrow at others' suffering), the two halves of Buddhist mercy. Buddhist Korean inherited this from Chinese sutras.

Mandarin bēi, 1st tone. 悲伤 (bēishāng, grief), 悲剧 (bēijù, tragedy), 慈悲 (cíbēi, mercy), 可悲 (kěbēi, lamentable / pitiable). Modern Chinese leans formal/literary with 悲 — everyday "sad" is 难过 (nánguò) or 伤心 (shāngxīn). Reserved for serious sorrow.

Japanese on-reading ヒ (hi) — 悲劇 (higeki, tragedy), 悲鳴 (himei, scream), 悲観 (hikan, pessimism). The kun-reading かなしい (kanashii, "sad") is the standard Japanese adjective for sadness, used freely in everyday speech: 悲しい映画 (kanashii eiga, a sad film). Pairs as the emotional opposite of 嬉しい (ureshii, happy). Japanese also has the noun form 悲しみ (kanashimi, sorrow / grief) — a more reflective, lingering form of sadness.

Memory aid: a heart shouting "no!" — protest against reality is what grief feels like.