蓝图
lántú · HSK 7
blueprint
📐📘 蓝 (blue) + 图 (diagram) = a blue diagram, i.e. a blueprint
A blueprint really was a blue-tinted technical drawing (cyanotype), so the Chinese name is literal: blue + diagram. By extension it means any design or master plan.
蓝 — grass radical 艹 + 監 (jiān, phonetic)
蓝 originally referred to the indigo plant used to make blue dye. The grass radical 艹 signals a plant, while 監 supplies the sound. Over time the meaning extended from the dye plant to the color blue itself.
图 — enclosure 囗 + 冬 (simplified from 啚)
Originally written 圖, showing an enclosure 囗 around 啚, a depiction of a granary or rural settlement on a map. The whole character meant a map or chart of demarcated territory. Meaning later broadened to picture, diagram, or to plan/scheme.