castillo
/kasˈtiʝo/ · B1 · noun · m
castle
🏰 castillo = castle + -illo: Latin castellum, a little fort (castrum)
Same root as English castle: Latin castellum, the diminutive of castrum (fort). Spanish kept the -ill- where English has -le. Castilla (Castile) means land of castles, so the word hides inside the region's name.