The partita began as a single-movement instrumental piece during the 16th century. By the 1700s it had evolved into a multi-movement piece, or air and variations, the term synonymous with the suite. The most famous are the Partitas of J. S. Bach for solo violin.
By the time of Mozart the term had been extended to include the Serenade, with one of Mozart’s greatest works being his "Gran Partita" for 13 wind instruments. In the early 19th century F. V. Krommer would write partitas for various combinations of wind instruments. The 20th century saw it grow even further. Ralph Vaughan Williams wrote a "Partita for Double String Orchestra", and William Walton took the term about as far as it could get from Bach’s solo violin pieces with a partita, commissioned by George Szell for the Cleveland Orchestra, that is scored for full orchestra with double woodwinds and various augmentations such as a glockenspiel.
Reference: “The Grove Concise Dictionary of Music”