To cry and sniffle in a weak, annoying way, especially when you are complaining or unhappy.
Sniveling is not a good thing. It makes people think you are weak or annoying.
Examples:
The baby started to snivel when she dropped her toy.
Stop sniveling and tell me what's wrong.
He always snivels when he doesn't get his way.
I don't want to hear you snivel about it.
She would snivel and snivel until she got what she wanted.
He sniveled all the way home from school.