any salt or ester of oxalic acid, occurring in plants, esp. spinach, rhubarb, and certain other vegetables and nuts, and capable of forming an insoluble salt with calcium and interfering with its absorption by the body.
ox·a·late (ŏk'sə-lāt') n. A salt or an ester of oxalic acid. tr.v.
ox·a·lat·ed, ox·a·lat·ing, ox·a·lates To treat (a specimen) with an oxalate or oxalic acid.