Available Definitions:
1) a. - Ranked or ranged below; subordinate; inferior; specifically (Mil.), ranking as a junior officer; being below the rank of captain; as, a subaltern officer.
2) a. - Asserting only a part of what is asserted in a related proposition.
3) n. - A person holding a subordinate position; specifically, a commissioned military officer below the rank of captain.
4) n. - A subaltern proposition.