http://www.askoxford.com/asktheexperts/faq/aboutwords/primary says: What comes after primary, secondary, tertiary? The sequence continues with quaternary, quinary, senary, septenary, octonary, nonary, denary. Words also exist for `twelfth order' (duodenary) and `twentieth order' (vigenary). ---------------------- But http://wiki.answers.com/Q/What_comes_after_quaternary says: What comes after quaternary? Quinary. The full list is unary, binary, tertiary, quaternary, quinary, after which it becomes ambiguous.

1) "primary (1) secondary (2) tertiary (3) quaternary (4) quinary (5) senary (6) septenary (7) octonary (8) nonary (9) denary (10) duodenary (12) vigenary (20)" Source and further information: http://en.wiktionary.org/wiki/quaternary Happily, by the US presidential election, after the primary, you only have the main election... 2) "There are two such ordinal lists that I deal with on a regular basis: the set beginning with first, and the set beginning with primary. I’m not in touch with the subset names (help, readers!), but as I see it, the first set shows spatial or chronological order, and the second set shows order of precedence or effect: Spatial/Chronological..............Precedence/Effect* first..............................................primary second.........................................secondary third............................................tertiary fourth.........................................quaternary fifth.............................................quinary sixth............................................senary seventh.......................................septenary eighth.........................................octonary ninth...........................................novenary tenth...........................................decenary" "In computer science, there does seem to be another stream of adjectives: unary, binary, and ternary." Source and further information: http://verbmall.blogspot.com/2007/01/ordinal-numbers-revisited.html