- Further (education) - Level of education - Primary, secondary, ... - third in degree of order - Third in degree or order - Being of the third formation, order, or rank; third; as,
a tertiary use of a word. - Possessing some quality in the third degree; having been
subjected to the substitution of three atoms or radicals; as, a
tertiary alcohol, amine, or salt. Cf. Primary, and Secondary.