The term 'less dense' can be described by four words: cleverer (8 letters), sparser (7 letters), airier (6 letters), and SMARTER (7 letters). Cleverer means having or showing intelligence, while sparser means having fewer parts or elements. Airier means lighter in weight or texture, and SMARTER means having or showing quickness of mind. Together, these words describe something that is less dense, meaning it has fewer parts, is lighter in weight or texture, and is more intelligent.