hexadecimalPronunciation: /ˌhɛksəˈdɛsɪm(ə)l/Definition of hexadecimal adjective Computing relating to or using a system of numerical notation that has 16 rather than 10 as its base: a string of hexadecimal charactersDerivatives hexadecimally adverb hexadecimal in other Oxford dictionaries Definition of hexadecimal in the US English dictionary