The Collaborative International Dictionary of English v.0.48:

Undulant \Un"du*lant\, a.
   Undulating. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

undulant
    adj 1: resembling waves in form or outline or motion [syn:
           undulatory, undulant]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "undulant":
   alternate, beating, bent, billowing, billowy, circling, curvaceous,
   curvate, curvated, curve, curved, curvesome, curviform,
   curvilineal, curvilinear, curving, curvy, cyclic, epochal, even,
   every other, geosynclinal, incurvate, incurvated, incurved,
   incurving, intermittent, isochronal, labyrinthine, mazy,
   meandering, measured, metronomic, oscillatory, periodical, pulsing,
   reciprocal, recurrent, recurring, recurvate, recurvated, recurved,
   recurving, rhythmic, rolling, rotary, seasonal, serial, serpentine,
   sinuous, steady, surgy, tortuous, undulate, undulated, undulating,
   undulative, undulatory, wavelike, waving, wavy, wheeling