trifluctuation

from The Collaborative International Dictionary of English v.0.48

Trifluctuation \Tri*fluc`tu*a"tion\, n. [Pref. tri- +
   fluctuation.]
   A concurrence of three waves. [Obs.] "A trifluctuation of
   evils." --Sir T. Browne.
   [1913 Webster] Trifoliate