[kas-uh
l, kah-suhl] 
noun, verb, -tled, -tling.| 1. | a fortified, usually walled residence, as of a prince or noble in feudal times. |
| 2. | the chief and strongest part of the fortifications of a medieval city. |
| 3. | a strongly fortified, permanently garrisoned stronghold. |
| 4. | a large and stately residence, esp. one, with high walls and towers, that imitates the form of a medieval castle. |
| 5. | any place providing security and privacy: It may be small, but my home is my castle. |
| 6. | Chess. the rook. |
| 7. | to place or enclose in or as in a castle. |
| 8. | Chess. to move (the king) in castling. |
| 9. | to move the king two squares horizontally and bring the appropriate rook to the square the king has passed over. |
| 10. | (of the king) to be moved in this manner. |