The Collaborative International Dictionary of English v.0.48:

June \June\, n. [L. Junius: cf. F. Juin. So called either from
   Junius, the name of a Roman gens, or from Juno, the goddess.]
   The sixth month of the year, containing thirty days.
   [1913 Webster]

         And what is so rare as a day in June?
         Then, if ever, come perfect days.        --Lowell.
   [1913 Webster]

   June beetle, June bug (Zool.), any one of several species
      of large brown beetles of the genus Lachnosterna and
      related genera; -- so called because they begin to fly, in
      the northern United States, about the first of June. The
      larv[ae] of the June beetles live under ground, and feed
      upon the roots of grasses and other plants. Called also
      May bug or May beetle.

   June grass (Bot.), a New England name for Kentucky blue
      grass. See Blue glass, and Illustration in Appendix.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Poa \Po"a\, n. [NL., fr. Gr. ? grass.] (Bot.)
   A genus of grasses, including a great number of species, as
   the kinds called meadow grass, Kentucky blue grass, June
   grass, and spear grass (which see).
   [1913 Webster]

WordNet (r) 3.0 (2006):

June grass
    n 1: valuable meadow and pasture grass in Europe and especially
         central United States having tall stalks and slender bright
         green leaves; a chief constituent in lawn grass mixtures
         [syn: Kentucky bluegrass, Kentucky blue, Kentucy blue
         grass, June grass, Poa pratensis]