n. The science of shells and shell-fish.n. The word came into use when mollusks were chiefly studied with reference to their shells. Since increased attention has been given to the structure of the soft parts of mollusks, the term conchology is frequently replaced by malacology (which see). Shells were formerly divided into three orders, univalves, bivalves, and multivalves, according to the number of parts of which they are composed.