Several parts combine into one character.

詩 is a phonetic-semantic compound: 言 (speech / word) on the left provides the meaning, while 寺 (sì, originally "government office" → later "Buddhist temple") on the right contributes the sound shī. The composite implication is "speech given a fixed form, governed by structural rule" — a poem. The 言 radical anchors the entire CJK vocabulary of language: 詩 (poem), 詞 (lyric / word), 誌 (record), 說 (to speak / explain), 語 (language / word), 訓 (to instruct).

Korean reading "si." 詩集 (sijip, poetry collection), 漢詩 (hansi, classical Chinese poetry — a separate genre in Korean letters from 시조 sijo, the native Korean form), 詩人 (siin, poet), 敍事詩 (seosasi, epic poem), 詩歌 (siga, poetry as a genre). Classical Chinese poetry is taught in Korean high schools as a distinct subject; memorizing Tang and Song poems by famous poets like Li Bai (李白) and Du Fu (杜甫) was historically a pillar of Korean Confucian education.

Mandarin shī, 1st tone (simplified 诗). 诗歌 (shīgē, poetry — pairing 诗 with 歌 song), 诗人 (shīrén, poet), 古诗 (gǔshī, ancient poem), 唐诗 (Táng shī, Tang Dynasty poetry). Tang poetry occupies a position in Chinese cultural memory roughly comparable to Shakespeare in English — a body of work that practically every literate Chinese person can quote at least a few lines from. The collection 唐诗三百首 (Tángshī sānbǎi shǒu, "Three Hundred Tang Poems") is the canonical anthology, memorized by generations of children.

Japanese on-reading シ (shi) — 詩 (shi, poem), 詩人 (shijin, poet), 叙事詩 (jojishi, epic), 詩集 (shishū, poetry collection). Japanese carefully distinguishes 詩 (shi) from native poetic forms: 短歌 (tanka), 俳句 (haiku), 川柳 (senryū) are native Japanese verse and not called 詩. The word 詩 in modern Japanese typically refers to free verse, translated foreign poetry, or classical Chinese poetry (漢詩 kanshi, which Japanese intellectuals composed in Classical Chinese for centuries).

Memory aid: speech (言) given the fixed structure of a temple (寺) — disciplined, formal language is a poem.