The Collaborative International Dictionary of English v.0.48:

Half tone \Half tone\, or Half-tone \Half"-tone`\, n.
   1. (Fine Arts) An intermediate or middle tone in a painting,
      engraving, photograph, etc.; a middle tint, neither very
      dark nor very light.
      [Webster 1913 Suppl.]

   2. (Music) A half step.
      [Webster 1913 Suppl.]

   3. A print obtained by the half-tone photo-engraving process.
      [WordNet sense 1]
      [PJC]

   4. the etched plate used to reproduce a half-tone
      illustration. [WordNet sense 4]

   Syn: halftone engraving, photoengraving.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Half-tone \Half"-tone`\ (h[aum]f"t[=o]n`), a.
   Having, consisting of, or pertaining to, half tones; specif.
   (Photo-engraving), pertaining to or designating plates,
   processes, or the pictures made by them, in which gradation
   of tone in the photograph is reproduced by a graduated system
   of dotted and checkered spots, usually nearly invisible to
   the unaided eye, produced by the interposition between the
   camera and the object of a screen. The name alludes to the
   fact that this process was the first that was practically
   successful in reproducing the half tones of the photograph.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

halftone
    n 1: a print obtained from photoengraving
    2: an engraving used to reproduce an illustration [syn:
       halftone, halftone engraving, photoengraving]

The Free On-line Dictionary of Computing (19 January 2023):

halftone

    The reproducion of greyscale images using dots
   of a single shade but varying size to simulate the different
   shades of grey.

   Laser printers that cannot print different sized dots,
   halftones are produced by varying the numbers of dots in a
   given area.

   This process is also used to produce a black and white version
   of a colour original using shades of grey in place of colours.

   See also device independent bitmap.

   (1996-09-20)