dissent, disagree, reject, disallow
It is not "assent", but good guess. A synonym for agree is "consent." You should usually only use the phrase "I consent" in a formal situation. "Dissent" is the antonym of "consent." Remember, there is no such word as "assent," and you should only use the phrase "I consent" in a formal situation.
Ascent is a homophone for assent.
Nodding your head often is a sign of assent in society
You have my assent to begin the procedure. Without your assent, we won't go.
she had to assent to comming to school on time
Assent as a verb: Assenting to her demands, I did as she requested. Assent as a noun: When told they were going to see The Avengers, Jayne nodded her assent.
I assent to your demands, sir.
A sailor's agreement or assent would be "aye."
his assent was bad
The team is seeking your official assent, but we'll go without it.
The patient had to assent to having the operation before the doctor could continue.
agreement agreement