أذان
Adhān
The call to prayer, proclaimed from the mosque five times a day.
What it means
Its words are “God is greater” four times, “I testify that there is no god but God”, “I testify that Muhammad is the messenger of God”, “come to prayer”, “come to success”, “God is greater”, and “there is no god but God”. At dawn the words “prayer is better than sleep” are added.
What the sources say
Reports in Abu Dawud and al-Tirmidhi say the wording was seen in a dream by the Companion Abdullah ibn Zayd, and the Prophet approved it and told Bilal, who had a fine voice, to give it. Sahih al-Bukhari relates that Muslims at first gathered without a call, and some suggested a bell like the Christians or a horn like the Jews; instead, a man was appointed to call.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 23, listed as ADHĀN. The definition is restated here.