I. |sekˌsen.|tenərē, (ˈ)sek|sent ə nˌerē adjective
Etymology: Latin sescenteni, sexcenteni six hundred each (from sex six + centeni one hundred each, from centum hundred) + English -ary — more at hundred
: relating to the number 600 or a 600th anniversary
II. noun
: a 600th anniversary or its celebration