Another word from the Core in High Wycombe, England. This one is an Alger original. It has many uses but primarily used as a greeting between select people. It's also used as a radar device i.e. someone will shout 'ah?' and others will reply 'ah?' so you can tell where each other are in a crowded room or something. However, similar to words like 'safe', it can be used in many situations and its meaning adapts itself to different situations.