On the platform, bibi comes up as grandmother, but it should be nyanya if i am not wrong. bibi is a wife
I really like this dictionary: www.glosbe.com/sw/en/nyanya
There are lots of entries and it's steadily growing, and even if there's no entry, there's a translation database so you can see things in context. Also, when there are lots of words, you can click on each one to see their back translations without leaving the page you're on.