Where does “Alentejo” come from?

Alentejo (Portuguese) comes from Portuguese além, from Old Portuguese alen, from Latin illinc, from Latin illim, from Latin ille, from Latin olle, from Proto-Italic *olnos — that.

Ancestry of “Alentejo”, step by step

Alentejo traces back through two separate lines of ancestry.

via Portuguese além

Step	Language	Word	Meaning
1	Portuguese	além	there, over there; beyond; the afterlife, the...
2	Old Portuguese	alen	—
3	Latin	illinc	thence; there
4	Latin	illim	thence
5	Latin	ille	that; those; "; demonstrative pronoun "; that...
6	Latin	olle	Archaic form of ille
7	Proto-Italic	*olnos	that

via Portuguese Tejo

Step	Language	Word	Meaning
1	Portuguese	Tejo	Tagus
2	Old Portuguese	Tejo	—
3	Latin	Tagus	—

Words derived from “Alentejo”

Alentejo
Alentejan
Alentejo
alentejano
alentejano

Every word from Proto-Italic *olnos →Every word from Latin olle →Every word from Latin ille →