hamza

noun

1. A sign (ء ‎(ʾ)‎ - a stand-alone hamza) used in the written Arabic language representing a glottal stop. Hamza may appear as a stand-alone letter or most commonly over or under other letters, e.g. أ ‎(ʾ)‎ (over an alif - ا‎), إ ‎(ʾ)‎ (under an alif), ؤ ‎(ʾ)‎ (over a wāw - و ‎(w)‎) or ئ ‎(ʾ)‎ (over a dotless yāʾ - ى‎). The exact seat of hamza is governed by an orthographic rule - "seat of hamza rule".