The Collaborative International Dictionary of English v.0.48:

July \Ju*ly"\, n.; pl. Julies. [L. Julius; -- named from Caius
   Julius Caesar, who was born in this month: cf. F. Juillet.]
   The seventh month of the year, containing thirty-one days.
   [1913 Webster]

   Note: This month was called Quintilis, or the fifth month,
         according to the old Roman calendar, in which March was
         the first month of the year.
         [1913 Webster]

WordNet (r) 3.0 (2006):

July
    n 1: the month following June and preceding August