Source : Webster's Revised Unabridged Dictionary (1913)

Prescutum \Pre*scu"tum\, n.; pl. {Prescuta}. [NL. See {Pr[ae]-},
   and {Scutum}.] (Zo["o]l.)
   The first of the four pieces composing the dorsal part, or
   tergum, of a thoracic segment of an insect. It is usually
   small and inconspicuous.