Dates Latin Key Words Months Days of the Week Latin English Latin English Januarius January dominica, dies dominuca, dominicus, dies Sunday Februarius February Solis, feria prima Martius March feria secunda, dies Lunae Monday Aprilis April feria tertia, dies Martis Tuesday Maius May feria quarta, dies Mercurii Wednesday Junius June feria quinta, dies Jovis Thursday Julius July feria sexta, dies Veneris Friday Augustus August feria septima, sabbatum, dies sabbatinus, Saturday September, 7ber, 7bris, VIIber September dies Saturni October, 8ber, 8bris, VIIIber October November, 9ber, 9bris, IXber November December, 10ber, 10bris, Xber December Numbers Phrases Indicating Time Roman Cardinal Ordinal Latin English Numeral anno domini in the year of the 1 unus 1st primus I Lord 2 duo, duae 2nd secundus II anno in the year (since/of) 3 tres, tres, tria 3rd tertius III incarnationis the incarnation of the 4 quattuor 4th quartus IV Lord 5 quinque 5th quintus V annus bissextus leap year 6 sex 6th sextus VI ante meridiem before noon (a.m.) 7 septem 7th septimus VII biduum space of two days, 8 octo 8th octavus VIII two-day period 9 novem 9th nonus IX cras tomorrow 10 decem 10th decimus X datum date, given 11 undecim 11th undecimus XI dies (diei) day 12 duodecim 12th duodecimus XII eiusdem die of the same day 13 tredecim 13th tertius decimus XIII eodem anno in the same year 14 quattuordecim 14th quartus decimus XIV eodem die on the same day 15 quindecim 15th quintus decimus XV eodem mense in the same month 16 sedecim 16th sextus decimus XVI mane in the morning 17 septemdecim 17th septimus decimus XVII mensis month 18 odeviginti 18th duodevicesimus XVIII meridie noon 19 undeviginti 19th undevicesimus XIX nocte at night 20 viginti 20th vicesimus or XX nudius tertius day before yesterday vigesimus post meridiem after noon (p.m.) 21 viginti unus 21st vicesimus primu XXI vespere in the evening 22 viginti duo 22th vicesimus secundus XXII 23 viginti tres 23th vicesimus tertius XXIII 24 viginti quattuor 24th vicesimus quartus XXIV 25 viginti quinque 25th vicesimus quintus XXV 26 viginti sex 26th vicesimus sextus XXVI 90 nonaginta 90th nonagesimus XC 27 viginti septem 27th vicesimus septimus XXVII 100 centum 100th centesimus C 28 viginti octo 28th vicesimus octavus XXVIII 200 ducenti 200th ducentesimus CC 29 viginti novem 29th vicesimus nonus XXIX 300 trecenti 300th trecentesimus CCC 30 triginta 30th tricesimus XXX 400 quadringenti 400th quadringentesimus CD 31 triginta unus 31th tricesimus primus XXXI 500 quingenti 500th quingentesimus D 40 quadraginta 40th quadragesimus XL 600 sescenti 600th sescentesimus DC 50 quinquaginta 50th quinquagesimus L 700 septigenti 700th septingentesimus DCC 60 sexaginta 60th sexagesimus LX 800 octingenti 800th octingentesimus DCCC 70 septuaginta 70th septuagesimus LXX 900 nongenti 900th nongentesimus CM 80 octoginta 80th octogesimus LXXX 1000 mille 1000th millesimus M Latin Key Words—April 2010 Copyright ©2010 IRI 1/1 .