The Collaborative International Dictionary of English v.0.48:

Peanism \Pe"an*ism\ (p[=e]"an*[i^]z'm), n. [Gr. paianismo`s, fr.
   paiani`zein to chant the p[ae]an.]
   The song or shout of praise, of battle, or of triumph. [R.]
   [1913 Webster]