The Collaborative International Dictionary of English v.0.48:

Influent \In"flu*ent\ ([i^]n"fl[-u]*ent), a. [L. influens,
   -entis, p. pr. of influere, influxum, to flow in; pref. in-
   in + fluere to flow. See Fluid.]
   1. Flowing in. "With influent tide." --Cowper. "Influent
      odors." --Mrs. Browning.
      [1913 Webster]

   2. Exerting influence; influential. [Obs.]
      [1913 Webster]

            I find no office by name assigned unto Dr. Cox, who
            was virtually influent upon all, and most active.
                                                  --Fuller.
      [1913 Webster]

WordNet (r) 3.0 (2006):

influent
    adj 1: flowing inward [syn: inflowing, influent]