Definition of vociferous:

conspicuously and offensively loud; given to vehement outcry

Synonyms of vociferous:

blatant, clamant, clamorous, strident, obstreperous, strident, noisy, boisterous

Opposite/Antonyms of vociferous:

quiet, diffident, bashful, meek, gentle, hushed, demure, cautious, tranquil

Sentence/Example of vociferous:

The crowd at the Halton Stadium can be a vociferous lot anyway, so we will have to be on our mettle.