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
ballade, ballad—a narrative "song": as in a literary ballad, poem, in the musical tradition of an art song, or to a one-movement instrumental piece with lyrical and dramatic narrative qualities reminiscent of such a song setting.
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
grazioso [I], con grazia, gratioso, graziös [G], Mit Grazie—graceful, gracefully; easy
moderato [I], moderamente, modéré [F], modérément [F]—moderately, at a moderate tempo, applying a touch of restraint to its related word(s), e.g. allegro moderato
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
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.