WordNet (r) 3.0 (2006):

wavelength
    n 1: the distance (measured in the direction of propagation)
         between two points in the same phase in consecutive cycles
         of a wave
    2: a shared orientation leading to mutual understanding; "they
       are on the same wavelength"

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "wavelength":
   amplitude, antinode, carrier, carrier wave, crest, de Broglie wave,
   diffraction, electric wave, electromagnetic radiation,
   electromagnetic wave, frequency, frequency band,
   frequency spectrum, ground wave, guided wave, hertzian wave,
   high-frequency wave, in phase, interference, light, long wave,
   longitudinal wave, low-frequency wave, mechanical wave, microwave,
   node, out of phase, period, periodic wave, radio wave, ray,
   reinforcement, resonance, resonance frequency, seismic wave,
   shock wave, shortwave, sky wave, sound wave, surface wave,
   tidal wave, transverse wave, trough, wave, wave equation,
   wave motion, wave number