An unseamed garment made of pastic.    From Wordnet, Princeton University. 

Verb (used with object) : to unseam a dress.    From Dictionary.com. 

And Clyde noted how one pocket on her dress drooped just a bit, becoming unseamed.    From Wordnik.com.  [Underworld] Reference

Marking ensues with pencil and straight edge in line with the sizes cited in the technical drawing or the widths of the unseamed plank edges.    From Wordnik.com.  [5. Circular Sawing Technology] Reference

His face, though unweathered and unseamed, and much too fine and thin in texture, had a curious affinity to the faces of old sailors or fishermen who have lived.    From Wordnik.com.  [The Patrician] Reference

They unseamed it from nave to chaps.    From Wordnik.com.  [2 The Slaughter of the Pig « Unknowing] Reference

  Another, hideous sight! unseamed appears.    From Wordnik.com.  [Childe Harold's Pilgrimage] Reference

Another, hideous sight! unseamed appears.    From Wordnik.com.  [The Works of Lord Byron. Vol. 2] Reference