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.
andante [I]—moderately slow tempo (e.g. walking). Faster than adagio but slower than allegretto
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
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
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
rondo—sectional movement form featuring a recurring refrain between contrasting episodes in a variety of plans, a typical one being ABACABA (A is the refrain; B and C are episodes). Often used for finales.
string quartet, Streichquartett [G], quatuor à cordes [F], quartetto d'archi [I], quartetto di cordi [I], cuarteto de cuerda [S], vonósnégyes [H]—ensemble or a work 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 | wiki
tema con variazioni, con variazioni, Tema e variazioni, theme and variations, Thema mit Variationen [G], Thème varié [F]—a common movement form featuring an initial theme followed by a series of variations on that theme, each of which adjusts any number of parameters to achieve variety, e.g. tempo, rhythm, key, instrumentation, etc.A challenge to the composers ingenuity and a delight for the listener
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.
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