Source : Webster's Revised Unabridged Dictionary (1913)

Mattock \Mat"tock\, n. [AS. mattuc; cf. W. matog.]
   An implement for digging and grubbing. The head has two long
   steel blades, one like an adz and the other like a narrow ax
   or the point of a pickax.

         'T is you must dig with mattock and with spade. --Shak.

Source : WordNet®

mattock
     n : a kind of pick that is used for digging; has a flat baled
         set at right angles to the handle