ADJECTIVE (1)

1. (of tempo) very fast;


ADVERB (2)

1. suddenly;
- Example: "Presto! begone! 'tis here again"- Swift

2. at a very fast tempo (faster than allegro);

The Collaborative International Dictionary of English v.0.48:

Presto \Pres"to\, adv. [It. or Sp. presto quick, quickly. See
   Prest, a.]
   1. Quickly; immediately; in haste; suddenly.
      [1913 Webster]

            Presto! begone! 'tis here again.      --Swift.
      [1913 Webster]

   2. (Mus.) Quickly; rapidly; -- a direction for a quick,
      lively movement or performance; quicker than allegro, or
      any rate of time except prestissimo.
      [1913 Webster]

WordNet (r) 3.0 (2006):

presto
    adv 1: suddenly; "Presto! begone! 'tis here again"- Swift
    2: at a very fast tempo (faster than allegro)
    adj 1: (of tempo) very fast

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "presto":
   accelerando, adagietto, adagio, affrettando, allegretto, allegro,
   andante, andante tempo, andantino, beat, compound time, con anima,
   con brio, crescendo, decrescendo, desto, diminuendo, duple time,
   expeditiously, flat-out, forte, fortissimo, full tilt, hastily,
   immediate, instant, instantaneous, larghetto, larghissimo, largo,
   legato, lickety-split, lightning-like, marcando, march tempo,
   mixed times, moderato, momentaneous, momentary, pianissimo, piano,
   pizzicato, posthaste, prestissimo, quick as lightning,
   quick as thought, quickly, rag, ragtime, rallentando, rapidly,
   ritardando, ritenuto, rubato, scherzando, scherzo, sextuple time,
   simple time, spiccato, staccato, stretto, syncopation, syncope,
   tempo, tempo rubato, three-quarter time, time, time pattern,
   timing, triple time, triplet, two-four time, veloce, vivace,
   vivacissimo, waltz time



The Free On-line Dictionary of Computing (30 December 2018):

PRESTO

   A parallel language for shared-memory multiprocessors, built
   on top of C++ by Bershad et al, U Washington 1987.  PRESTO
   provides classes for threads and spinlocks as well as
   Mesa-style monitors and condition variables.

   (ftp://cs.washington.edu/pub/presto1.0.tar.Z).  E-mail:
   .

   ["PRESTO: A Kernel for Parallel Programming Environments",
   B.N. Bershad et al, U Wash CS TR, Jan 1987].