かあさん【母さん】 : kaasan | define meaning
Region: Kanto (Tokyo)
(Familiar) A term of endearment used to refer to the mother in a family: "Mom; mum; mama; momma; mommy; mother".
"a mom getting by"
ne, kaasan, yamete yo!
"Mom, quit it!"
Context and nuance are key to understanding: a child calling his own mom "kaasan" in a light tone will be perceived as endearing; a teenager speaking in an objecting tone or over the internet is more likely to use this form to denigrate their mother (as opposed to using the honorific form おかあさん【お母さん】 okaasan).