What does "pupa" mean?

Pupa: (Zoöl.) A genus of air-breathing land snails having an elongated spiral shell. Coarctate, or Obtected, pupa, a pupa which is incased in the dried-up skin of the larva, as in many Diptera. -- Masked pupa, a pupa whose limbs are bound down and partly concealed by a chitinous covering, as in Lepidoptera.