Castle in the air, a visionary project; a baseless scheme; an air castle; -- sometimes called a castle in Spain (F. ChÔteau en Espagne).
Syn. -- Fortress; fortification; citadel; stronghold. See Fortress.
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.
Cas"tle*build`er (?), n. Fig.: one who builds castles in the air or forms visionary schemes.
-- Cas"tle*build`ing, n.
Cas"tled (?), a. Having a castle or castles; supporting a castle; as, a castled height or crag.