Found one definition

  1.                 From Japanese-English FreeDict Dictionary ver. 0.1:
                    

    (ateji (phonetic) reading) 治具, (ateji (phonetic) reading) (word containing irregular kanji usage) 冶具, じぐ, () ジグ (noun (common) (futsuumeishi))

    Note: word usually written using kana alonejig (tool)