(1) A compound that resembles another in structure but is not necessarily an isomer (e.g., 5-fluorouracil is an analogue of thymine); analogues are often used to block enzymatic reactions by combining them with enzymes (e.g., isopropyl thiogalactoside vs. lactose). (2) One of two organs or parts in different species of animals or plants that differ in structure or development but are similar in function. [G. analogos, proportionate]