duodecimal
Concise Oxford English Dictionary © 2008 Oxford University Press:
duodecimal /ˌdjuːə(ʊ)ˈdɛsɪm(ə)l/
▶adjective relating to or denoting a system of counting or numerical notation that has twelve as a base.
– derivatives
duodecimally adverb.
duodecimally adverb.
'duodecimal' also found in these Oxford entries:

