四角い
しかくい · shikakui · JLPT N2 · i-adj
square
🟥 四角い = 四 (four) + 角 (corner) + い (adjective ending): four corners, so square
角 (kaku) means corner or horn. 四角 is four corners, and the い ending turns it into an adjective meaning square-shaped.
四 — enclosure 囗 + divide 八
Originally 四 was written as four horizontal strokes (亖), a simple tally for the number four. The current form, showing 八 (divide) inside an enclosure 囗, was borrowed during the Zhou dynasty and gradually replaced the older tally form. The shape is unrelated to its meaning today.
角 — pictograph of a horn
角 is a pictograph of an animal's horn, with early oracle-bone forms clearly showing the curved, ridged shape of a horn. From 'horn' it extended to mean corner, angle, and by metaphor a role or part (as in a stage role). The reading jiǎo covers most of these senses.