A Hundred and One Rules in Arabic Grammar!

72. The Plural Vocatives   أيـُّها  and أيـَّتـُها ==================================================

You have already been introduced to the vocative  يا , which is used with singular nouns and, therefore, could be followed by a proper noun, a title, or an Idaafa, regardless of the gender.

The plural forms show gender distinction and, therefore, Arabic has أيـُّها  for the masculine and   أيـَّتـُها for the feminine. The plural vocative should be followed by a noun with the definite article in the nominative case.