the.com/opus
A creative work serious enough to demand a Latin number.
means A single artistic work, especially a musical or literary one, often presented as a creator's major effort.
from Straight from Latin opus, meaning work or labor — the same root that gives you opera (literally the plural, works) and the cooperative grind of operate.
Catalog toolOpus numbers track a composer's works chronologically.
Magnum opusLatin for greatest work, a career-defining masterpiece.
Posthumous quirkSome opus numbers were assigned after composers died.