as·sev·er·ate 
(ə-sĕvə-rāt′)
(ə-sĕvə-rāt′)tr.v. as·sev·er·at·ed, as·sev·er·at·ing, as·sev·er·ates
To declare seriously or positively; affirm.
[Latin assevērāre, assevērāt- : ad-, ad- + sevērus, serious; see segh- in the Appendix of Indo-European roots.]
as·sev′er·ation n.
as·sever·a′tive (-ə-rātĭv, -ər-ə-tĭv) adj.