Source : Webster's Revised Unabridged Dictionary (1913)

Nisan \Ni"san\, n. [Heb. n[=i]s[=a]n.]
   The first month of the jewish ecclesiastical year, formerly
   answering nearly to the month of April, now to March, of the
   Christian calendar. See {Abib}.

Abib \A"bib\, n. [Heb. ab[=i]b, lit. an ear of corn. The month
   was so called from barley being at that time in ear.]
   The first month of the Jewish ecclesiastical year,
   corresponding nearly to our April. After the Babylonish
   captivity this month was called {Nisan}. --Kitto.

Source : WordNet®

Nisan
     n : the seventh month of the civil year; the first month of the
         ecclesiastic year (in March and April) [syn: {Nissan}]