Where does “gravísimamente” come from?

gravísimamente (Spanish) comes from Spanish gravísimo, from Spanish gravé, from Old Spanish grave, from Latin gravis, from Proto-Indo-European gʷréh₂us, from Proto-Indo-European -us — Forms adjectives from Caland system roots.

Ancestry of “gravísimamente”, step by step

Step	Language	Word	Meaning
1	Spanish	gravísimo	superlative degree of grave
2	Spanish	gravé	serious, grave
3	Old Spanish	grave	—
4	Latin	gravis	heavy; troublesome, hard; grave, serious
5	Proto-Indo-European	gʷréh₂us	heavy
6	Proto-Indo-European	-us	Forms adjectives from Caland system roots

Every word from Proto-Indo-European -us →Every word from Proto-Indo-European gʷréh₂us →Every word from Latin gravis →