n.1. An acidic glycosaminoglycan found especially in lung and liver tissue and having the ability to slow the clotting of blood, used as a drug in the treatment of thrombosis. Also called unfractionated heparin.
2. Any of several anticoagulants, such as enoxaparin, that are derived from this compound by depolymerization and have a lower molecular weight and somewhat different pharmacological properties. Also called low-molecular-weight heparin.