adagio [It]—slow tempo, often implying a lyrical, poignant character
allegretto—moderately quick tempo. slower than allegro but faster than andante
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
marcia [I], alla marcia, marche [F], Marsch [G], march [E], marciale, marziale—march, in the manner of a march, e.g. duple meter at a moderate but deliberate pace in a manner which may be proud, grand, like a parade or a show of military bravado.
passacaglia, passacaille [F], pasacalle [S]—A variation form based on a recurring bass line or chord progression closely related to the chaconne. Of Spanish origin first appearing in the early 17th century. Some generalizations suggest a grave character, a minor key and a triple meter. wiki
quartet, quatuor [F], quartett [G], quartetto [I]—ensemble or work for four players the most important examples being the string quartet and the piano quartet
quasi—almost, almost like, as if
serioso [I], serio—serious, grave, tragic
string quartet, Streichquartett [G], quatuor à cordes [F], quartetto d'archi [I], quartetto di cordi [I]—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.
tempo, tempi [pl]—speed or pace at which music progresses. Traditional classic music typically uses standard Italian words to designate the tempo, e.g. Allegro or adagio. Metronome markings provide precise numerical speeds. Tempo selection during performance is a complex artistic choice informed by composer's markings, performance tradition, technical limitations and interpretation.