in-concessus, a, um, adj.,
not allowed , impossible (not ante-Aug. and rare): hymenaei, unlawful , forbidden , Verg. A. 1, 651; cf. ignes, Ov. M. 10, 153: spes, id. ib. 9, 638: cum totum exprimere paene sit homini inconcessum, Quint. 10, 2, 26.
in-concessus adj., not allowed, unlawful, forbidden: hymenaei, V.: ignes, O.: spes, O. ...
An Elementary Latin Dictionary