de·fin·i·tive di-'fin-ət-iv adj fully differentiated or developed <a \definitive organ>
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de·fin·i·tive (də-finґə-tiv) 1. established with certainty. 2. in embryology, denoting acquisition of final differentiation or character. 3. in parasitology, denoting the host in which a parasite reaches the sexual stage.Medical dictionary. 2011.