WordNet (r) 3.0 (2006):

hydroponics
    n 1: a technique of growing plants (without soil) in water
         containing dissolved nutrients [syn: hydroponics,
         aquiculture, tank farming]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "hydroponics":
   agrarianism, agricultural geology, agriculture, agrology,
   agronomics, agronomy, algology, aquiculture, botany, bryology,
   contour farming, cultivation, culture, dendrology, dirt farming,
   dry farming, dryland farming, farm economy, farming, fruit farming,
   fungology, geoponics, grain farming, husbandry, intensive farming,
   mixed farming, mycology, paleobotany, phycology,
   physiological botany, phytobiology, phytochemistry, phytoecology,
   phytogeography, phytography, phytology, phytomorphology, phytonomy,
   phytopaleontology, phytopathology, phytotaxonomy, phytoteratology,
   phytotomy, phytotopography, plant anatomy, plant pathology,
   plant physiology, pomology, rural economy, sharecropping,
   strip farming, structural botany, subsistence farming,
   systematic botany, tank farming, thremmatology, tillage, tilth,
   truck farming