The word for grandma is "isoäiti", at least in sentences like "I went to visit my grandma last weekend". Monikers such as "mummo" are borrowed from Swedish, which means that not too long ago, the finnish language seems to have been without any "mama"-related words. Which is more interesting than the fact that some of those have been borrowed into modern day finnish, since it shows that "mama" is not a universal feature of all languages.
> Monikers such as "mummo" are borrowed from Swedish, which means that not too long ago, the Finnish language seems to have been without any "mama"-related words.
I'm not sure we can conclude that? Borrowings can displace existing words, so the current state of the vocabulary doesn't necessarily tell you what was there before.
As a slightly related example in German: 'Base' and 'Vetter' for your girl and boy cousins have been replaced in the last few decades with the French borrowings 'Cousine' (also spelled 'Kusine') and 'Cousin' (also spelled 'Kuseng'). Looking just at the current vocabulary, you might conclude that German did not have specific words for these people until the French come along.
Germans also replaced 'Muhme' and 'Oheim' with 'Tante' and 'Onkel'.
Fun aside: the English word 'boss' has etymological ties with the German 'Base'. (English got 'boss' from Dutch.)
I’ve never heard “Base” (only “Kusine”) for female cousin, but still usually hear “Vetter” for male cousin, and “Vettern” for multiple cousins of mixed gender.