The Collaborative International Dictionary of English v.0.48:

Prepollent \Pre*pol"lent\, a. [L. praepollens, p. p. of
   praepollere to surpass in power; prae before + pollere to be
   powerful.]
   Having superior influence or power; prevailing; predominant.
   [R.] --Boyle.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prepollent \Pre*pol"lent\, n.; pl. Prepollices. [NL. See
   Pre-, Pollex.] (Anat.)
   An extra first digit, or rudiment of a digit, on the preaxial
   side of the pollex.
   [1913 Webster]