tercentenary Meaning, Definition & Usage

  1. noun the 300th anniversary (or the celebration of it)
    tercentennial; triennial.

WordNet

Ter*cen"te*na*ry adjective
Etymology
L. ter thirce + E. centenary.
Definitions
  1. Including, or relating to, an interval of three hundred years. -- n. The three hundredth anniversary of any event; also, a celebration of such an anniversary.

Webster 1913