The article focuses on the Nyaya-Vaisesika (NV) category called abhava. Presence (bhava) and absence (abhava) are the basis of the padarthas or categories in the NV tradition. In English translations of the NV literature, this category and its subdivision are translated as relational absence and mutual absence or difference. The three kinds of relational absence are prior-absence, posterior-absnece and constant absence. Also included are examples of prior-absence.