From The Collaborative International Dictionary of English v.0.48 :
Privateersman \Pri`va*teers"man\ (pr[imac]`v[.a]*t[=e]rz"man),
n.; pl. Privateersmen (pr[imac]`v[.a]*t[=e]rz"men).
An officer or seaman of a privateer.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
privateersman
n 1: an officer or crew member of a privateer [syn: privateer,
privateersman]