In linguistics, ordinal numbers are the words representing the rank of a number with respect to some order, in particular order or position (i.e. first, second, third, etc.). Its use may refer to size, importance, chronology, etc. In English, they are adjectives.
They are different from the cardinal numbers (one, two, three, etc.) referring to the quantity.
Ordinal numbers are alternatively written in English with numerals and letter suffixes: 1st, 2nd or 2d, 3rd or 3d, 4th, 11th, 21st, 101st, 477th, etc. In some countries, written dates omit the suffix, although it is nevertheless pronounced. For example: 5 November 1605 (pronounced "the fifth of November ... "); November 5, 1605, ("November Fifth ..."). When written out in full with "of", however, the suffix is retained: the 5th of November. In other languages, different ordinal indicators are used to write ordinal numbers.
In American Sign Language, the ordinal numbers first through ninth are formed with handshapes similar to those for the corresponding cardinal numbers with the addition of a small twist of the wrist.[1]
Spatial or chronological ranks will use the standard linguistic ordinal numbers first, second, etc.; however, the ranking of precedence or effect often uses primary, secondary, etc.[2] and historical rankings in literature, biology or music may use Greek prefixes, e.g., Proto-Isaiah, Deutero-Isaiah, Subjugalis ebdomi (seventh subjugation)[3], endacato tergite (eleventh ring)[4]. The first twelve variations of ordinal numbers are given here.
| Spatial/Chronological | first | second | third | fourth | fifth | sixth | seventh | eighth | ninth | tenth | eleventh | twelfth |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Precedence/Effect | primary | secondary | tertiary | quaternary | quinary | senary | septenary | octonary | novenary | decenary | undecenary | duodecenary |
| Greek Prefix | proto- | deutero- | trito- | tetrado- | pempto- | ecto- | ebdomo- | ogdoo- | enato- | decato- | endecato- | dudecato- |
When speaking the numbers in fractions, the spatial/chronological numbering system is frequently used for denominators larger than 2. This system results in "two thirds" for 2/3 and "fifteen thirty-seconds" for 15/32. This system is normally used for denominators less than 100 and for many powers of 10. Examples include "six ten-thousandths" for 6/10,000 and "three hundredths" for 0.03.