arrowslit
nounEtymology From arrow + slit.
1
A slit, as in a castle wall, through which arrows can be fired.
- When they met in the church tower the gaps in their fragmentary conversation were filled up. […] They sat talking for hours on the dusty, twig-littered floor, one or other of them getting up from time to time to cast a glance through the arrowslits and make sure that no one was coming.1949, George Orwell, chapter 3, in Nineteen Eighty-Four: