Pronounced: tran-SPICK-yoo-uhs, adj
Notes: I was pretty close, but not quite right on this one
The word opusculum means “a minor word (as of literature)”; a variant of it is opuscule.
This word comes from Latin: many of us probably know opus (work). This word is the diminutive form of opus. In English, opus usually refers to a musical piece, although it can refer to any literary or artistic work. Thus, opusculum refers to a short or minor work, but it is not restricted to music; in fact, it is rarely used for musical works. The plural of opus is opera, which came to English via Italian.
Irritatingly, opusculum didn’t have a first used, but its variant has a date of the mid-1600s, so I assume both words came together.