undefended

From un- +‎ defended.

undefended (comparative more undefended, superlative most undefended)

1. Not defended.
   • 1969 March 31, Kurt Vonnegut, Jr., Slaughterhouse-Five […] (A Seymour Lawrence Book), New York, N.Y.: Delacorte Press, →OCLC, page 127:

     “You needn’t worry about bombs, by the way. Dresden is an open city. It is undefended, and contains no war industries or troop concentrations of any importance.”