Balsam is a thick, sweet-smelling resin — a kind of balm — that certain trees make, and it is also the name of the tree that produces it. People have long used it in perfume and in old-fashioned medicine; you meet it in church language and in plant names more than in street talk. The English word came from Latin balsamum, from Greek, and that from a Semitic word for spice or perfume. Balm is the same word that came into English by a shorter, older path; they are doublets. Though actually, balsam is not related to balsa, the light wood, even though the two look like cousins on the page.