Receptor affinity refers to the strength with which a drug or ligand attaches to a receptor site. Some synonyms for receptor affinity include binding strength, receptor binding affinity, receptor-ligand interaction, receptor specificity, and receptor selectivity. The term receptor binding affinity suggests the attraction or adhesion between the receptor and ligand. Receptor specificity and selectivity refer to the ability of a drug to bind to a particular receptor and its selectivity for that receptor over other receptors. Receptor-ligand interaction suggests the dynamic and complex interaction between the receptor and its ligand. These synonyms are essential in pharmacology and drug development, as the receptor affinity of a drug can determine its potency and effectiveness.