allegro [I]—fast, lively tempo. From the Italian word for cheerful or gay.
andante [I]—moderately slow tempo (e.g. walking). Faster than adagio but slower than allegretto
assai—very much. Intensifies the direction of its neighboring words, e.g. "allegro assai", very fast
chamber music, Kammermusik [G], musique de chambre [F], musica da camera [I], musica cameralis [L]—"Classical Music" for a small ensemble, generally 8 or fewer players with a canonical emphasis on 3-6 players. explore
lento, lent [F], lentement [F], avec lenteur [F]—slow (tempo)
opus [L], opera[pl], Op., Opp, WoO, Op. posth—work, as in a work of art. For unique identification, publishers/composers often assign an "opus number", abbreviated as "Op." (e.g. Op. 1). A range of works by opus number, uses the plural "opp." (e.g. "Opp. 1-3"). A single opus number may refer to a collection of works (e.g. a set of quartets) giving rise to designations like "Op. 1, No. 4". For misc. works without opus numbers, "WoO" is often used (e.g."Without Opus"). Posthumously assigned numbers may use "Op. posth". Opus numbers may not precisely reflect chronology (publication vs. composition), can be erroneous, sparse or duplicative. Thus, the works of some historically important composers may use separate catalog numbers (e.g. Bach, Haydn, Schubert). See wiki
quintet, quintette [F], quintett [G], quintetto [I]—an ensemble / work for 5 players, the typical examples being string quintet (with second viola or cello), piano quintet or woodwind quintet
string quintet, quintette à cordes [F], quintetto d'archi [I], Streichquintett [G], quinteto de cuerdas [S]—ensemble (work) for 5 string players, the string quartet plus guest. The additional instrument might be a viola, cello or bass. The most common choices are named: Viola Quintet, Cello Quintet.
troppo [I], non troppo, trop [F]—too, too much. non troppo means "not too much". e.g. "Allegro ma non troppo" means fast, but not too much