The Collaborative International Dictionary of English v.0.48:

Upstroke \Up"stroke`\, n.
   An upward stroke, especially the stroke, or line, made by a
   writing instrument when moving upward, or from the body of
   the writer, or a line corresponding to the part of a letter
   thus made.
   [1913 Webster]

         Some upstroke of an Alpha and Omega.     --Mrs.
                                                  Browning.
   [1913 Webster]

WordNet (r) 3.0 (2006):

upstroke
    n 1: a stroke normally made in an upward direction