In Cisco IOS, an Access Control List is used to identify IP Addresses when used for filtering, route-maps and so on. This is abbreviated as ACL. The letters ACL appears so often in writing and discussions that most Network Engineers no longer say “Access Control List” but attempt to make a word out of ACL – thus “ackle” is the sound of the acronym as a word.
“Ackle” means ACL means Access Control List.
Note: Similar terms exist is many other parts of IT such “Sequel” for SQL.