* Quiet: This is a general antonym, meaning not loud or noisy.
* Silent: Similar to quiet, this implies a complete lack of sound.
* Reserved: This suggests a person who is reluctant to speak or express their opinions.
* Subdued: This describes something that is quiet and restrained.
* Taciturn: This describes someone who is habitually silent or quiet.
* Mellow: This implies a calm and gentle demeanor, the opposite of boisterous.
The best antonym for "vociferous" will depend on the specific situation and the meaning you want to convey.