The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]