Source : Webster's Revised Unabridged Dictionary (1913)

Ironsides \I"ron*sides"\, n. ?
   A cuirassier or cuirassiers; also, hardy veteran soldiers; --
   applied specifically to Cromwell's cavalry.

Source : WordNet®

Ironsides
     n : English general and statesman who led the parliamentary army
         in the English Civil War (1599-1658) [syn: {Cromwell}, {Oliver
         Cromwell}]