Entry 1 sense Webster, 1913 Coadunation · Co·ad·u·na·tion · IPA /kəʊˌædjʊˈneɪʃən/ 01 n. Union, as in one body or mass; unity. 1. Union, as in one body or mass; unity. “The coadunation of all the civilized provinces.” — Coleridge.