The Collaborative International Dictionary of English v.0.48:

Hewn \Hewn\, a.
   1. Felled, cut, or shaped as with an ax; roughly squared; as,
      a house built of hewn logs.
      [1913 Webster]

   2. Roughly dressed as with a hammer; as, hewn stone. Hex

The Collaborative International Dictionary of English v.0.48:

Hew \Hew\ (h[=u]), v. t. [imp. Hewed (h[=u]d); p. p. Hewed
   or Hewn (h[=u]n); p. pr. & vb. n. Hewing.] [AS.
   he['a]wan; akin to D. houwen, OHG. houwan, G. hauen, Icel.
   h["o]ggva, Sw. hugga, Dan. hugge, Lith. kova battle, Russ.
   kovate to hammer, forge. Cf. Hay cut grass, Hoe.]
   1. To cut with an ax; to fell with a sharp instrument; --
      often with down, or off. --Shak.
      [1913 Webster]

   2. To form or shape with a sharp instrument; to cut; hence,
      to form laboriously; -- often with out; as, to hew out a
      sepulcher.
      [1913 Webster]

            Look unto the rock whence ye are hewn. --Is. li. 1.
      [1913 Webster]

            Rather polishing old works than hewing out new.
                                                  --Pope.
      [1913 Webster]

   3. To cut in pieces; to chop; to hack.
      [1913 Webster]

            Hew them to pieces; hack their bones asunder.
                                                  --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hewn
    adj 1: cut or shaped with hard blows of a heavy cutting
           instrument like an ax or chisel; "a house built of hewn
           logs"; "rough-hewn stone"; "a path hewn through the
           underbrush" [syn: hewn, hand-hewn]