The Collaborative International Dictionary of English v.0.48:

Kern \Kern\, v. t. [imp. & p. p. Kerned; p. pr. & vb. n.
   Kerning. ] (Type Founding)
   To form with a kern. See 2d Kern.
   [1913 Webster]

The Free On-line Dictionary of Computing (30 December 2018):

kerning
kern

    In typography, the process of adjusting the spacing
   between certain pairs of characters to improve the appearance of
   the text.  Roughly speaking, this can be thought of as equalising
   the area of space between adjacent characters.  Each character
   of a proportional font has a width that includes some space on
   either side so that adjacent letters don't touch.  Some pairs of
   characters such as A and V, look better if the spaces overlap
   slightly, bringing the characters closer together (but still not
   touching).  In most cases, kerning reduces the spacing ("negative
   kerning") but some pairs like "r" and "y" look better with extra
   space ("positive kerning").

   See also tracking, leading.

   (2014-01-14)