adagio [It]—slow tempo, often implying a lyrical, poignant character
allegretto—moderately quick tempo. slower than allegro but faster than andante
allegro [I]—fast, lively tempo. From the Italian word for cheerful or gay.
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
molto [It]—very much
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
poco, un poco, poco a poco—a little bit, e.g. "andante un poco moto" is andante with a little more motion than typical. "poco a poco" means a little bit at a time, gradually.
quartet, quatuor [F], quartett [G], quartetto [I], cuarteto [S]—ensemble or work for four players the most important examples being the string quartet and the piano quartet
string quartet, Streichquartett [G], quatuor à cordes [F], quartetto d'archi [I], quartetto di cordi [I], cuarteto de cuerda [S], vonósnégyes [H]—an ensemble as well as music written for that ensemble comprising 2 violins, viola and cello. This is one of the essential genres / forms / ensembles of chamber music and arguably a critical "core" of "classical" music. Explore the string quartet.
trio (2)—The middle section of three-part (ternary) forms such as the minuet and scherzo yielding the structure: Minuet - Trio - Minuet (repeat). The trio often brings contrast by change of key, tempo, mood or texture i.e. a shift in instrumental scoring.