Colours, shapes and sizes

Six colours have an i-adjective beside the noun: 赤(あか)い, 青(あお)い, 白(しろ)い, 黒(くろ)い, and 黄色(きいろ)い and 茶色(ちゃいろ)い, which keep their 色(いろ). Every other colour is a noun only and joins another noun with の: 緑(みどり)の傘(かさ), ピンクのシャツ. One trap for English speakers: 青(あお) is blue, but in a few fixed uses it also covers green — a green traffic light is 青(あお). Size and weight adjectives turn into nouns with 〜さ: 長(なが)い, long; 長(なが)さ, length.