■ noun
1》 a large building, typically of the medieval period, which is (or was formerly) fortified as a stronghold.
2》 Chess, informal old-fashioned term for rook 2 .
■ verb Chess move one's king from its original square two squares along the back rank towards a rook on its corner square which is simultaneously moved to the square passed over by the king.
Phrases
~s in the air (or in Spain ) visionary unattainable schemes; daydreams.
Derivatives
~d adjective
Origin
OE: from Anglo-Norman Fr. and Old North. Fr. castel , from L. castellum , dimin. of castrum 'fort'.