§27. Root, Stem, and Base
The Base is that part of a word which is unchanged in inflection: as, serv- in servus; mēns- in mēnsa; īgn- in īgnis.
a. The Base and the Stem are often identical, as in many consonant stems of nouns (as, rēg- in rēg-is). If, however, the stem ends in a vowel, the latter does not appear in the base, but is variously combined with the inflectional termination. Thus the stem of servus is servo-; that of mēnsa, mēnsā-; that of īgnis, īgni-.
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.