字 (Kanji for letter)

Onyomi

As a child, JESUS Christ wrote lots of letters on his tiny crown. Mostly, he wrote "Who is my Daddy?"

漢字(かんじ)	kanji ★★★★★ 漢 (Chinese) + 字 (letter) = 漢字 (kanji) of course
文字(もじ)	a letter ★★★★☆ FP 文 (culture/ sentence) + 字 (letter) = 文字 (a letter) a letter- whether kana, kanji, or alphabet.
ローマ字(ろうまじ)	western, Roman letters. A,b,c,d,y,o,m,a,m,a ★★★☆☆ マ () + 字 (letter) = ローマ字 (western, Roman letters. A,b,c,d,y,o,m,a,m,a)
数字(すうじ)	a numeral - 1,2,3, etc. ★★★☆☆ 数 (integer, to count) + 字 (letter) = 数字 (a numeral - 1,2,3, etc.)

The CHILD can only write one letter.

There's a THOUSAND cosmoses in string theory.
The MOHICAN punker has a knowledge of @narchy.