A concertino is a short concerto freer in form. It normally takes the form of a one-movement musical composition for solo instrument and orchestra, though some concertinos are written in several movements played without a pause.
ConCertino is also the name of a filk music

Filk music

Filk is a musical culture, genre, and community tied to science fiction/fantasy fandom and a type of fan labor. The genre has been active since the early 1950s, and played primarily since the mid-1970s. The term predates 1955.-Definitions:As the Interfilk What Is Filk page demonstrates, there is...

 convention held in Massachusetts.

In classical music a concertino is:

• Concertino (group)
  Concertino (group)
  A concertino is the smaller group of instruments in a concerto grosso. This is opposed to the ripieno which is the larger group contrasting with the concertino....
  
   — the smaller group of instruments in a concerto grosso
  Concerto grosso
  The concerto grosso is a form of baroque music in which the musical material is passed between a small group of soloists and full orchestra...
  
  .
• Concertino (composition)
  Concertino (composition)
  A concertino is a short concerto freer in form. It normally takes the form of a one-movement musical composition for solo instrument and orchestra, though some concertinos are written in several movements played without a pause....
  
   — a short concerto
  Concerto
  A concerto is a musical work usually composed in three parts or movements, in which one solo instrument is accompanied by an orchestra.The etymology is uncertain, but the word seems to have originated from the conjunction of the two Latin words...
  
  .

In ballet Concertino refers to one of two ballets danced by New York City Ballet

New York City Ballet

New York City Ballet is a ballet company founded in 1948 by choreographer George Balanchine and Lincoln Kirstein. Leon Barzin was the company's first music director. Balanchine and Jerome Robbins are considered the founding choreographers of the company...

:

• Concertino (Balanchine) by George Balanchine)
• Concertino (Robbins) by Jerome (Robbins)