一
イチ, イツ, ひと, ひと.つ, かず, い, いっ, いる, かつ, かづ, てん, はじめ, ひ, ひとつ, まこと

one, one radical (no.1)

JLPT5 G1 S1 F2

Although 一 is sometimes said to represent an outstretched finger, the phonetic evidence suggests the fundamental idea is that of its cognate 壹 (unity of contents). 一 may therefore be regarded as an abstract representation of unity, or fullness → *one*.

[Full Kanji Etymology List]