In your psych eval, if you came across the phrase Substance Abuse: denies you might be insulted. It sounds as if the evaluator has decided that you do abuse substances, but refuse to admit it. It doesn't mean that at all, it just means you said you didn't. If the evaluator knew something to the contrary, she would include it: but tox screen is positive for cannabinoids. Denies suicidal ideation. Denies auditory and visual hallucinations. The evaluator is not going to write "none" in any of those slots, because she doesn't know that.
The income tax system is voluntary in the US. That doesn't mean you can opt to not pay it. It means you fill out the bill yourself rather than having the government send you one.
A better known example is that acute doesn't mean intense, it means brief, or coming on quickly. Culture has a different meaning in the social sciences than it does in everyday use. Actually, culture has a slightly different meaning in each social science class you'll ever take.
Words with specific meanings in a subject (in legalese a term of art, which is, I suppose, a term of art in the law) cause a great deal of headache when they move out of their own neighborhoods. Well-meaning people blunder, crusaders mislead many, and the deceptive misuse terms intentionally to manipulate.
Christian theology has its own pitfalls here. Personal God is often misunderstood.
Here's an irony: in Critical Theory, such terms are often seen as tools of
oppression. But critical in this sense not only has a different meaning than the everyday, it has a different meaning than its specific literary usage. Postmodern vocabulary (and its deconstructionist and poststructuralist cousins), is perhaps the best known example of using language as a tool of oppression.