tertius

From Proto-Indo-European *tr̥tyós ~ *tritós, ordinal form of *tréyes. Akin to Ancient Greek τρίτος (trítos), Proto-Germanic *þridjô and Proto-Slavic *tretь.

• (Classical) IPA^(key): /ˈter.ti.us/, [ˈt̪ɛrt̪iʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈter.t͡si.us/, [ˈt̪ɛrt̪͡s̪ius]

tertius (feminine tertia, neuter tertium); first/second-declension numeral

1. third, the ordinal number after secundus (“second”) and before quārtus (“fourth”)
   • For quotations using this term, see Citations:tertius.

• In a poetic sense it is used for the Roman "Third World", that is the "Underworld", of Pluto

First/second-declension adjective.

• “tertius”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “tertius”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• tertius in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• tertius in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• Carl Meißner, Henry William Auden (1894) Latin Phrase-Book‎, London: Macmillan and Co.
  • it is the third hour (= 9 A.M.: tertia hora est
    
  • I am in my thirteenth year: tertium decimum annum ago
    
  • to be middle-aged (i.e. between thirty and forty): tertiam iam aetatem videre
    
  • to admit another into the circle of one's intimates: aliquem (tertium) ad (in) amicitiam ascribere
    
  • the actor who plays the leading part: actor primarum (secundarum, tertiarum) partium
    
  • consul for the second, third time: iterum, tertium consul