Refers to a single written character, such as a kanji, kana, or letter of the alphabet. Often used when discussing spelling, writing, or the number of characters in a word.
この言葉は一字足りない。
This word is missing one character.
Indent the beginning of a paragraph by one character.
彼は一字も間違えずに書いた。
He wrote it without making a single character mistake.
These two words differ by just one character.
There wasn't a single mistake in his letter.
一字 is the standard modern word for 'one written character,' while 一文 is a limited, old-fashioned use of the same idea.
word for word; verbatim; literally
letter by letter; character by character
word of great value; each word worth a thousand pieces of gold
a single word; (not even) a word or syllable
leave a space between words; put a space
Compound of 一 (one) and 字 (character, letter). The reading いちじ follows standard on'yomi.