Source : Webster's Revised Unabridged Dictionary (1913)

Incunabulum \In`cu*nab"u*lum\, n.; pl. {Incunabula}. [L.
   incunabula cradle, birthplace, origin. See 1st {In-}, and
   {Cunabula}.]
   A work of art or of human industry, of an early epoch;
   especially, a book printed before a. d. 1500.