tertium adv.
tertius, for the third time : etiam iterum ac tertium: creatis tribunis, L.
tertĭum, adv., v. tertius, B. fin. ...
A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
·add. ·- A third somewhat; something mediating, or regarded as being, between two diverse or incompa...
Webster's Dictionary of the English Language