taru-adjective, adverb taking the 'to' particle
the whole house in uproar; the entire audience in commotion
Describes a situation where everyone present becomes agitated, noisy, or stirred up at once. Often used in news reports or literary descriptions of assemblies, meetings, or performances.
The venue was thrown into an uproar at his sudden resignation announcement.
The stands erupted in commotion over the referee's puzzling call.
騒然 alone means 'noisy' or 'in an uproar'; 満場騒然 specifies that the uproar involves the entire venue or audience.
A four-character compound combining 満場 (whole venue) and 騒然 (in an uproar). The exact historical derivation is uncertain, but it follows a common pattern of Sino-Japanese compounds used in formal writing.