The Collaborative International Dictionary of English v.0.48:
Prairial \Prai`ri`al"\, n. [F., fr. prairie meadow.] The ninth month of the French Republican calendar, which dated from September 22, 1792. It began May, 20, and ended June 18. See Vendemiaire. [1913 Webster]WordNet (r) 3.0 (2006):
Prairial n 1: ninth month of the Revolutionary calendar (May and June); the month of meadows