The Collaborative International Dictionary of English v.0.48:

Gyronny \Gy"ron*ny\ (j[imac]"r[o^]n*n[y^]), a. [F. gironn['e].]
   (Her.)
   Covered with gyrons, or divided so as to form several gyrons;
   -- said of an escutcheon.
   [1913 Webster]