The reading of お母さん


beginner in Japanese here. I was curious about why you read the Kanji in お母さん
(O **kā** san) differently from just 母 (Haha). I know that there's Kun and On
reading but I can't find this Kanji read as "kā" in both readings.




Kun: はは (haha, 母, Jōyō); はわ (hawa, 母); は (ha, 母); あも (amo, 母); おも (omo, 母); かか
(kaka, 母); かあ (kā, 母) from wiktionary
<https://en.wiktionary.org/wiki/%E6%AF%8D> [Etymology 7 has more information
on the かあ reading.](https://en.wiktionary.org/wiki/%E6%AF%8D)

