The word 'undeniably' is built upon the core verb 'deny', which originates from the Latin denegare, meaning to refuse or say no completely. The addition of the prefix 'un-' negates the action, creating the adjective 'undeniable' to describe something that cannot be refused or contradicted. Finally, the adverbial suffix '-ably' transforms it into a modifier describing the manner of an action, resulting in the modern meaning of "in a manner that cannot be denied," conveying absolute certainty and irrefutability.

Structure: un (not) + deny (refuse to admit) + ably (in a manner that can be) - un: A prefix of Germanic origin (Old English) meaning "not," used to form negatives. - deny: A verb from Old French denier, from Latin denegare (to deny, refuse), from de- (completely) + negare (to say no, refuse). - ably: An adverbial suffix from Latin -abilis (able to be) via Old French -able, combined with the adverbial suffix -ly (in a specified manner).