是
shì · HSK 1
to be
☀️ 是 = 日 (sun) over 正 (correct) — what's under the sun is true
Top 日 is sun, bottom is a variant of 正 (upright/correct). Originally meant 'correct, right', then shifted to the copula 'to be'. Memory hook: under the sun, it's correct — it is so.
是 — sun 日 + 正 (correct/upright)
Originally a compound suggesting 'the sun 日 directly overhead'—straight, correct, true. From this concrete sense of 'right' or 'this very thing,' 是 came to mean 'this' as a demonstrative, and later the modern copula 'to be / is.' The 'correct' meaning survives in words like 是非 (right and wrong).