indulgeo.

From in- and an unattested verb *dulgeō, from Proto-Italic *dolɣēō, from Proto-Indo-European *delǵʰ- (“to become fixed”); cognate with Welsh dala (“to catch”), Gothic 𐍄𐌿𐌻𐌲𐌾𐌰𐌽 (tulgjan, “to reinforce”), and perhaps Sanskrit दृह् (dṛh, “to make firm”). The initial in- may be, instead of the above, derived from a negated form of an unattested adjectival Proto-Indo-European *n-dlgʰ-ro- (“not hard”), thus giving indulgeō an original meaning of "to not be hard toward" > "to be lenient toward" > "to indulge". This is semantically smoother than if the "in-" were to mean "in". Possibly related to longus, Ancient Greek ἐνδελεχής (endelekhḗs, “continuous”), thus originally with the meaning of "being persistent, patient".