Where does “fillastre” come from?
fillastre (Catalan) comes from Latin fīliaster, from Latin fīlius, from Old Latin fīlios, from Proto-Indo-European dʰeh₁y-li-os, from Proto-Indo-European dʰeh₁(y)- — to suckle, nurse.
fillastre (Catalan): stepson
Ancestry of “fillastre”, step by step