character spacing; space between letters or characters
Refers to the horizontal or vertical space between adjacent characters in typography, design, or handwriting.
字間を広げると文章が読みやすくなる。
Increasing the character spacing makes the text easier to read.
このフォントは字間が狭すぎる。
The character spacing of this font is too narrow.
行間 is the space between lines of text, while 字間 is the space between individual characters.
Compound of 字 (character) and 間 (space, interval).