Where does “hidalgo” come from?

hidalgo (Romanian) comes from French hidalgo, from Spanish hidalgo, from Old Spanish fidalgo, from Old Spanish fijo, from Latin fīlius, from Old Latin fīlios, from Proto-Indo-European dʰeh₁y-li-os, from Proto-Indo-European dʰeh₁(y)- — to suckle, nurse.

hidalgo (Romanian): hidalgo