adagio [It]—slow tempo, often implying a lyrical, poignant character
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
divertimento [I], divertissement [F]—amusement, diversion, entertainment, even table music; Typically, a suite of movements (often more than 4) often intended for diversion and pleasure of a lighthearted nature suitable for social occasions. Typically implies a smaller chamber ensemble. The name was common in 18th century for a variety of music, some of which was more serious and profound than its title would suggest. The French divertissement can apply to an entr'acte: dances and airs from other acts.
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.