'Tertiary syphilis' definitions:

Definition of 'tertiary syphilis'

noun

The third stage; characterized by involvement of internal organs especially the brain and spinal cord as well as the heart and liver

From: GCIDE

Tertiary \Ter"ti*a*ry\, a. [L. tertiarius containing a third part, fr. tertius third: cf. F. tertiaire. See Tierce.]
1. Being of the third formation, order, or rank; third; as, a tertiary use of a word. --Trench. [1913 Webster]
2. (Chem.) 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. [1913 Webster]
3. (Geol.) Later than, or subsequent to, the Secondary. [1913 Webster]
4. (Zool.) Growing on the innermost joint of a bird's wing; tertial; -- said of quills. [1913 Webster]
Tertiary age. (Geol.) See under Age, 8.
Tertiary color, a color produced by the mixture of two secondaries. "The so-called tertiary colors are citrine, russet, and olive." --Fairholt.
Tertiary period. (Geol.) (a) The first period of the age of mammals, or of the Cenozoic era. (b) The rock formation of that period; -- called also Tertiary formation. See the Chart of Geology.
Tertiary syphilis (Med.), the third and last stage of syphilis, in which it invades the bones and internal organs. [1913 Webster]