as·sev·er·ate /əˈsɛvəˌreɪt/

-verb (used with object), -at·ed, -at·ing.
to declare earnestly or solemnly; affirm positively; aver.

[Origin: 1785-95; < L assevérātus spoken in earnest (ptp. of assevérāre), equiv. to as- as- + sevér- (see severe) + –ātus -ate1]

-Synonyms assert, state, maintain.

Source: Dictionary.com.

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