Other forms: classmates
A classmate is someone who sits in the same class as you. The boy two desks along who lends you a pencil; the woman you shared a table with in evening Spanish.
The word says nothing about friendship — a classmate can be someone you never speak to in three years. English builds a whole family this way: flatmate, roommate, teammate, workmate, schoolmate, shipmate, each one the person you share the thing with. Keep classmate and schoolmate apart: the same class in one, the same school in the other. In American English classmate stretches to everyone who finished university in the same year, so a college classmate may be someone you last saw at graduation. It is one word with no hyphen, and the plural is classmates.
1nounclassmateA person who is in the same class as you at school or college.
“Her classmates all signed the card.”
2nounfinishedIn American English, someone who finished a course or degree in the same year as you.
“He hired an old classmate from law school.”
classmate is a fellow student.
Nothing is hidden here: class plus mate. Mate is the ending English reaches for when it wants the person you share something with — a flat, a team, a ship, a classroom.
Latin
classis
Middle French
classe
English
class
English, today
classmate
From class + mate. class Borrowed from Middle French classe, from Latin classis. From Middle French classe, from Latin classis (“a class or division of the people, assembly of people, the whole body of citizens called to arms, the army, the fleet, later a class or division in general”), from Proto-Indo-European kelh₁- (“to call, shout”). a doublet of clas and classis. ġecynd.
Etymology from Wiktionary, CC BY-SA