Fr.: sous-ensemble propre
Of two sets A and B, the set A if it is contained in B (A ⊂ B) but is not equal to B (A ≠ B).
A set of elements wholly contained in another set. If each element of a set A belongs to a set B, A is called a subset of B, written A ⊂ B or B ⊃ A and read "A is contained in B" or "B contains A" respectively.