Definition of "affirm" []

To declare positively or firmly; maintain to be true. (verb-transitive)
To support or uphold the validity of; confirm. (verb-transitive)
Law To declare solemnly and formally but not under oath. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Use "affirm" in a sentence

"The sun does not more certainly shine in the heavens, than that which I now affirm is true."
"Christ came into existence before Abraham did (as Arians affirm is the meaning), but that He never came into being at all, but existed before"
"The sun does not more certainly shine in the heavens, than that which I now affirm is true (30). ["

Words like "affirm"

affirmation affirmative affirmatively affirmed affirming affirms

assert asseverate assure aver avouch back

confirm demonstrate deny document establish pronounce

protest prove ratify shew verify vouch