A letter is an element of an alphabet. A collection of letters forms a word.
Letter
See also
Alphabet, Code, Codeword, WordThis entry contributed by David Terr
Explore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W., with contributions by David Terr. "Letter." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Letter.html