coming from, being on, or directed toward, the side; as, collateral pressure.-acting in an indirect way.-related to, but not strictly a part of, the main thing or matter under consideration; hence, subordinate; not chief or principal; as, collateral interest; collateral issues.-tending toward the same conclusion or result as something else; additional; as, collateral evidence.-descending from the same stock or ancestor, but not in the same line or branch or one from the other; -- opposed to lineal.-a collateral relative.-collateral security; that which is pledged or deposited as collateral security.