bel·fry 
/ˈbɛlfri/ noun
plural bel·fries /ˈbɛlfri/ noun [count] : a tower or part of a tower where a bell or set of bells hangs
bats in the/your belfry
informal + old-fashioned ◊To have bats in the belfry or (chiefly US) bats in your belfry is to be crazy.
▪ an old woman with bats in her belfry [=a crazy/batty old woman]
▪ an old woman with bats in her belfry [=a crazy/batty old woman]
