Where does “Grão-Pará” come from?

Grão-Pará (Portuguese) comes from Portuguese grão, from Old Portuguese grão, from Latin grānum, from Proto-Italic grānom, from Proto-Indo-European ǵr̥h₂nóm, from Proto-Indo-European ǵr̥h₂nós, from Proto-Indo-European ǵerh₂- — to grow old, to mature.

Grão-Pará (Portuguese): equivalent to the modern states of Amazonas, Amapá and Pará

Definitions

equivalent to the modern states of Amazonas, Amapá and Pará

Ancestry of “Grão-Pará”, step by step

Grão-Pará traces back through two separate lines of ancestry.

via Portuguese grão

Step	Language	Word	Meaning
1	Portuguese	grão	grain; grand; great; grand-
2	Old Portuguese	grão	—
3	Latin	grānum	grain, seed, small kernel
4	Proto-Italic	grānom	grain
5	Proto-Indo-European	ǵr̥h₂nóm	grain
6	Proto-Indo-European	ǵr̥h₂nós	matured, grown old
7	Proto-Indo-European	ǵerh₂-	to grow old, to mature

via Old Tupi pará

Step	Language	Word	Meaning
1	Old Tupi	pará	sea; wide river
2	Proto-Tupi-Guarani	*para	—

Every word from Proto-Indo-European ǵerh₂- →Every word from Proto-Indo-European ǵr̥h₂nós →Every word from Proto-Indo-European ǵr̥h₂nóm →