正式
せいしき · seishiki · JLPT N3 · na-adj
formal
📜 正式 = correct (正) + style/ceremony (式): done the proper way
正 means correct or proper, as in 正しい (tadashii, right). 式 means a set form or ceremony, as in 結婚式 (wedding). So 正式 is the proper form of doing something: official, formal. Contrast 非公式 (unofficial).
正 — one 一 + stop 止
Originally an ideograph showing a foot (止) advancing toward a target line (一), meaning 'to march straight toward' a city or goal. From this came the senses 'upright,' 'correct,' and 'proper.' The military sense survives in 征 (to campaign), which took over the original 'march' meaning.
式 — 工 (work) + 弋 (phonetic)
式 is a phono-semantic compound: 工 ('work, craft') gives the meaning of a tool, rule, or method, while 弋 supplies the sound. It originally referred to a standard pattern or model used in craftsmanship, then broadened to mean 'style, form, ceremony, or formula.'