cas·tle 
(kăsəl)
(kăsəl)n.
1.
a. A large fortified building or group of buildings with thick walls, usually dominating the surrounding country.
b. A fortified stronghold converted to residential use.
c. A large ornate building similar to or resembling a fortified stronghold.
2. A place of privacy, security, or refuge.
3. Games See rook2.
v. cas·tled, cas·tling, cas·tles
v.intr.
Games
Games
To move the king in chess from its own square two empty squares to one side and then, in the same move, bring the rook from that side to the square immediately past the new position of the king.
v.tr.
1. To place in or as if in a castle.
2. Games To move (the king in chess) by castling.
[Middle English castel, from Old English and from Norman French, both from Latin castellum, diminutive of castrum; see kes- in the Appendix of Indo-European roots.]
castleRaglan Castle near Raglan, Wales