By extension of the basic meaning of the root, "to cover", the term is used in the Quran in the senses of ignore/fail to acknowledge and to spurn/be ungrateful [REF].
According to the E. J. Brill's First Encyclopaedia of Islam, 1913-1936, Volume 4, the term first applied in the Quran to unbelieving Meccans, who endeavoured "to refute and revile the Prophet".