Opus

Opus is a Latin noun meaning "work" and is used in several distinct contexts to denote a published or contained piece within a larger body of work. In classical music, opus numbers (abbreviated op.) are cataloging labels assigned by publishers to individual compositions or groups of related works within a composer’s output. They provide a conventional ordering and reference system, but they are not universal; different composers and publishers have varied catalog practices, and some works lack opus numbers altogether. The term also survives in phrases such as opus magnum, referring to a person’s most significant achievement, and in discussions of a composer’s overall body of work.

In contemporary technology, Opus most prominently refers to the Opus audio codec. This open, royalty-free audio coding format is designed for interactive speech and general audio transmission. It was standardized by the Internet Engineering Task Force as RFC 6716. Opus combines two coding technologies, SILK for speech and CELT for general audio, and supports a wide range of bitrates and sample rates up to 48 kHz. Its low latency and versatility have led to widespread use in real-time communications, including VoIP, video conferencing, and streaming, with broad adoption in WebRTC and other platforms.

The name Opus also appears in various brands, products, and cultural references, but in encyclopedia context the primary senses are the Latin meaning related to works and catalogs, and the modern Opus audio codec with its technical and practical significance.