A famous example its the Arabic language where the the definite article al assimilates to one half of the potential following consonants called Sun letters in Arabic grammar. So it is an-Nil "the Nile" or ash-shams "the sun", but al-qamar "the moon".

A famous example is the Arabic language where the the definite article al assimilates to one half of the potential following consonants called Sun letters in Arabic grammar. So it is an-Nil "the Nile" or ash-shams "the sun", but al-qamar "the moon".