From The Collaborative International Dictionary of English v.0.48 [gcide]:
Castle \Cas"tle\, v. i. [imp. & p. p. Castled; p. pr. & vb. n.
Castling.] (Chess)
To move the castle to the square next to king, and then the
king around the castle to the square next beyond it, for the
purpose of covering the king.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Castled \Cas"tled\, a.
Having a castle or castles; supporting a castle; as, a
castled height or crag.
[1913 Webster]
2. Fortified; turreted; as, castled walls.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
castled
adj 1: having or resembling repeated square indentations like
those in a battlement; "a crenelated molding" [syn:
embattled, battlemented, castled, castellated]