It slides effortlessly from allegro to adagio, the pace quickening and slowing with each turn.
allegro non troppo the first movement is in the concerto variant of sonata form.
British Dictionary definitions for allegro
allegro
/əˈleɪɡrəʊ; -ˈlɛɡ-/
adjective, adverb
1.
(to be performed) quickly, in a brisk lively manner
noun (pl) -gros
2.
a piece or passage to be performed in this manner
Word Origin
C17: from Italian: cheerful, from Latin alacer brisk, lively
Word Origin and History for allegro
1680s as a musical term, from Italian allegro "cheerful, gay," from Latin alacrem (nominative alacer) "lively, cheerful, brisk" (see alacrity).
allegro in Culture
allegro [(uh-leg-roh, uh-lay-groh)]
A brisk, lively musical tempo. Allegro is Italian for “cheerful.”
allegro in Technology
operating system The code name for the major Mac OS release due in mid-1998. (https://devworld.apple.com/mkt/informed/appledirections/mar97/roadmap.html). (1997-10-15)