Describing someone who says what they think loudly, strongly, and often — and refuses to be quiet about it. A vociferous critic, a vociferous supporter, vociferous opposition, vociferous protests. It is a common word in news writing. Notice what it really points at: not simply volume, but insistence made public. A vociferous opponent of a plan writes letters, speaks at meetings, and shows up again next week. It is usually neutral to slightly disapproving, depending on whether the writer is on that person's side; "vociferous demands" can sound like reasonable pressure or like noise, and the surrounding sentence decides which. It describes people, groups, and the things they do, but not quiet feelings — you cannot be vociferously worried in your head. Related to the rare verb "vociferate", but this adjective is fully alive and ordinary in formal English.