If you're refering to Mozart's Clarinet Concerto then the instruments are Flute, Bassoon, Horn in A, Clarinet in A, Violin 1, Violin2, Viola, Violoncello, and Contrabass.

Gerald Strang has written:

'Concerto for 'cello with woodwinds and piano' -- subject(s): Concertos (Violoncello with instrumental ensemble)

violin

clarinet

ciello

kontrabas

violoncello

Yes, the full name of the 'cello is the violoncello.

The Cello is short for the Violoncello. The Cello evolved from the viola da gamba or Viol.

I hope that answered your question and the double base is not the violonbase, it is just a double base.