- any letter, as bā or mīm, representing a consonant that does not assimilate the l of a prefixed definite article.
Compare sun letter.
Origin of moon letter
translation of Arabic al-ḥuruf al-qamorīyah, so called from the use of al-qamar (the moon) to illustrate nonassimilation of l in al the
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018