§85. Gender in the Third Declension
Masculine are nouns in -or, -ōs, -er, -ĕs (gen. -itis), -ex (gen. -ĭcis): as, color, flōs, imber, gurges ( gurgitis), vertex ( verticis).
Exceptions are the following:—
a. Feminine are arbor; cōs, dōs; linter.
b. Neuter are ador, aequor, cor, marmor; ōs ( ōris); also os ( ossis);
cadāver, iter, tūber, ūber, vēr; and names of plants and trees in -er: as, acer, papāver.
J. H. Allen and J. B. Greenough, New Latin Grammar (Boston: Ginn, 1903). Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities.