Letter Run is a term used to describe a sequence of letters in the English alphabet. The crossword solutions for the term Letter Run are STU (3 letters), CDE (3 letters), LMN (3 letters), NOP (3 letters), QRS (3 letters), RST (3 letters), MNOP (4 letters), QRST (4 letters), and RSTU (4 letters). These solutions represent a sequence of letters that begins with S and ends with U, with each letter being followed by the next letter in the alphabet.