From The Collaborative International Dictionary of English v.0.48 :
Strapper \Strap"per\, n.
1. One who uses strap.
[1913 Webster]
2. A person or thing of uncommon size. [Colloq.]
[1913 Webster]
From WordNet (r) 3.0 (2006) :
strapper
n 1: a large and strong and heavyset man; "he was a bull of a
man"; "a thick-skinned bruiser ready to give as good as he
got" [syn: bull, bruiser, strapper, Samson]