Provided are an etchant, a method for fabricating a wire using the etchant, and a method for fabricating a thin film transistor (TFT) substrate using the etchant. The etchant includes a material having the formula 1, ammonium acetic acid, and the remainder of deionized water, wherein the formula 1 is expressed by: M(OH).sub.XL.sub.Y (1) where M indicates Zn, Sn, Cr, Al, Ba, Fe, Ti, Si, or B, X indicates 2 or 3, L indicates H.sub.2O, NH.sub.3, CN, COR, or NH.sub.2R, Y indicates 0, 1, 2, or 3, and R indicates an alkyl group.