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
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
quattro [I], a quattro—four; in four parts
sonata [I], sonate [pl], suonato—Originally, "sounded" rather than "sung" (sonar vs. cantar), i.e. instrumental music. According to historical period, sonata began to imply a formal plan of movements as well as the structure within a single movement, e.g. "sonata form" and applies to instrumental sonatas, string quartets, symphonies, etc., all examples of the sonata principle. In general usage as a specific work title (e.g. violin sonata), it designates a multi-movement piece for solo or duo instruments with one of the instruments enjoying a feature role. wiki
spirito, con spirito, spiritoso, spirituoso—Spirited, lively
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.