1. A woman who is like a mother to someone, providing maternal care, guidance, and affection, typically someone other than one's biological mother
My aunt has been a second mother to me since my parents divorced.
Minha tia tem sido uma segunda mãe para mim desde que meus pais se divorciaram.
2. A stepmother or adoptive mother
After the wedding, his stepmother became his second mother in every way that mattered.
Após o casamento, sua madrasta se tornou uma segunda mãe em todos os aspectos que importavam.