In argument to deny something is to state that some other claim is not true or that a particular state-of-affairs is not the case or that a specified principle does not apply, etc. That an hypothesis is denied is to show it is negated, refuted, or contradicted.

(see also: contradict, refutation, reasoning, reasonableness»rational, critical thinking, falsification, argument, soundness, problem of adequacy, persuasion/persuasiveness, fallacy, reasoning, conclusion, claim, evidence, (hidden) assumptions, establish, support, ground, justification, controversies, reasonableness, critical thinking, falsification)