When a masculine word ends in अ, इ, ई, उ, ऊ, it does not change in the plural :
So बाल (child) will be बाल (children)
When a masculine word ends in आ, change it to ए to make it plural :
काला (black singular) = कालो (black plural)
When a feminine word ends in अ or आ, change it to एँ :
रात (dark sing.) = रातों (dark plu.)
When a feminine word ends in या, change it to याँ :
कुटिया (shack) = कुटियाँ (shacks)
When a feminine word ends in इ or ई, change it to इयाँ :
बिल्ली (cat) = बल्लियाँ (cats)
When a feminine word ends in उ, ऊ, औ change it to एँ :
गौ (cow) = गौएँ (cows)
Some singular words don’t change in the plural :
मामा (uncle) = मामा (uncles)
There are some masculine words that don’t follow any rules when they change in the feminine form :
पिता (father) = माता (mother)


