Latin Ordinal Numbers

Latin ordinal numbers are ordered numbers: as in other Indo-European languages, they are adjectives which refer to the order of a set of objects in a list. English ordinals are words like "first", "second", "third", expressed in Latin "primus," "secundus," "tertius."

In contrast, cardinal numbers are nouns which tell you how many objects there are. Cardinal numbers in Latin are "unus," "duo," "tres"; English versions of those are "one," "two," "three."

Variations

The ordinal numbers in Latin are declined like first and second declension adjectives. There are some oddities to note:

• Some versions of the numbers have a variable presence of "n" before "s" and both spellings are acceptable
• for "21st" in the feminine, you might see una et vicesima "twenty-first" or the contracted form unetvicesima.

For other compounds, as in English, different texts use different versions. You may see the larger number before the smaller with no conjoining "​et" or you might see the smaller before with larger separated by the conjunction "et". Thus, you may see either vicesimus quartus (twenty-fourth, with the et) or quartus et vicesimus (four and twenty, with the et). For 28th, the Latin ordinal number is based on the idea of taking 2 from 30 or duodetricensimus, just as the duo de '2 from' precedes 20th in the ordinal number for 18th: duodevicesimus.

Primus Through Decimus

Below are listed the basic ordinal numbers in Latin with the Roman numeral corresponding to their value and their English equivalent.

• Roman Numeral | Ordinal | English Translation
• I. | primus (-a, -um) | first
• II. | secundus, alter | second
• III. | tertius | third
• IV. | quartus | fourth
• V. | quintus | fifth
• VI. | sextus | sixth
• VII. | septimus | seventh
• VIII. | octavus | eighth
• IX. | nonus | ninth
• X. | decimus | tenth

Undescimus Through Nonus Decimus

Variations are present in the Latin ordinals for tenth through nineteenth. If that seems strange, recall that English ordinals for 11th (eleventh) and 12th (twelfth) are formed differently than higher ones (thirteenth through nineteenth).

• Roman Numeral | Ordinal | English Translation
• XI. | undecimus | eleventh
• XII. | duodecimus | twelfth
• XIII. | tertius decimus or decimus et tertius | thirteenth
• XIV. | quartus decimus or decimus et quartus | fourteenth
• XV. | quintus decimus or decimus et quintus | fifteenth
• XVI. | sextus decimus or decimus et sextus | sixteenth
• XVII. | septimus decimus or decimus et septimus | seventeenth
• XVIII. | duodevice(n)simus, also octavus decimus | eighteenth
• XIX. | undevice(n)simus, also nonus decimus | nineteenth

Ac Deinceps Exortis et Superiora Loca

Ordinals higher than 20th follow the same patterns and variations as those seen in first through nineteenth.

• Roman Numeral | Ordinal | English Translation
• XX. | vice(n)simus | twentieth
• XXI. | unus et vice(n)simus, also vicesimus primus | twenty-first
• XXII. | alter et vice(n)simus or vicesimus secundus | twenty-second
• XXX. | trice(n)simus or trigesimus | thirtieth
• XL. | quadrage(n)simus | fortieth
• L. | quinquage(n)simus | fiftieth
• LX. | sexage(n)simus | sixtieth
• LXX. | septuage(n)simus | seventieth
• LXXX. | octoge(n)simus | eightieth
• XC. | nonage(n)simus | ninetieth
• C. | cente(n)simus | hundredth
• CC. | ducente(n)simus | two-hundredth
• CCC. | trecentensimus | three-hundredth
• CCCC. | quadringentensimus | four-hundredth
• D. | quingentensimus | five-hundredth
• DC. | sescentensimus | six-hundredth
• DCC. | septingentensimus | seven-hundredth
• DCCC. | octingentensimus | eight-hundredth
• DCCCC. | nongentensimus | nine-hundredth
• M. | millensimus | thousandth
• MM. | bis millensimus | two-thousandth