The Collaborative International Dictionary of English v.0.48:

Mezzotint \Mez"zo*tint\, n. [Cf. F. mezzo-tinto.]
   A manner of engraving on copper or steel by drawing upon a
   surface previously roughened, and then removing the roughness
   in places by scraping, burnishing, etc., so as to produce the
   requisite light and shade. Also, an engraving so produced.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mezzotint \Mez"zo*tint\, v. t.
   To engrave in mezzotint.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mezzotint
    n 1: print produced by an engraving that has been scraped to
         represent light or shade