**hexadecimal**: n. Base 16. Coined in the early 1950s to replace earlier sexadecimal, which was too racy and amusing for
stuffy IBM, and later adopted by the rest of the industry.

Actually, neither term is etymologically pure. If we take binary to be paradigmatic, the most
etymologically correct term for base 10, for example, is
‘denary’, which comes from ‘deni’ (ten at a time,
ten each), a Latin distributive
number; the corresponding term for base-16 would be something like
‘sendenary’. “Decimal” comes from the combining
root of decem, Latin for 10. If wish
to create a truly analogous word for base 16, we should start with
sedecim, Latin for 16. Ergo,
sedecimal is the word that would have
been created by a Latin scholar. The ‘sexa-’ prefix is Latin
but incorrect in this context, and
*‘hexa-*’ is Greek. The word octal is similarly incorrect; a correct form
would be ‘octaval’ (to go with decimal), or
‘octonary’ (to go with binary). If anyone ever implements a
base-3 computer, computer scientists will be faced with the unprecedented
dilemma of a choice between two *correct* forms; both
ternary and trinary have a claim to this throne.