word meaning associating something with Allah Subhana wa Ta'ala
("Glorified and Exalted be He"), i.e., worshipping other than God
alone or polytheism
. This is the only sin, if not repented from prior to death, which God has said is unforgivable
. From the Qur'an
Surely, Allah does not forgive associating anything with Him, and He forgives whatever is other than that to whomever He wills. (al-Nisa 4:48 and 116)
One who commits this sin is a mushrik
The paramount duty of the sincere worshipper is not ascribing any partners to God. This includes acribing to him a child or a mate.