1.NounThe amount of space between adjacent text characters.
2.NounThe practice of typing a letterspace in between the letters of a word (for emphasis) or an abbreviation (for delimitation), which in current orthographies and styles tends to be limited (to only certain uses).
"The typewritten identification papers from 1942 recorded the surname as A C K E R M A N N, with capitals and letterspacing.; The typewritten memo from 1952 referred to the CIA as the C. I. A., with periods and letterspacing."