gʰer-eyo-
“to keep desiring, craving”greedy, greed, yearn
Iterative yielding English greedy, greed, yearn from sense of insatiable wanting.
Discussion
The PIE form *gʰer-eyo- (to keep desiring, craving, yearning) is an iterative derivative of *gʰer- (to desire, to like, to be pleased), with the *-eyo- suffix expressing sustained or habitual wanting. The root generated the vocabulary of desire, favour, and thankfulness across several branches.
The Germanic branch preserves the root in English yearn (OE giernan/geornan, "to desire eagerly, to long for"), from PGmc *gernijaną. German gern(e) (gladly, willingly — "I do it gern" means "I do it with desire/pleasure") preserves the adverbial sense: doing something gern is doing it because you desire to. The connection between desiring and willingness is the root's semantic core.
Greek khaírein (χαίρειν, "to rejoice, to be glad, to take pleasure") continues the root in the Hellenic branch. The derivative kháris (χάρις, "grace, favour, gratitude, beauty") became one of the most important words in Greek philosophy, theology, and aesthetics: charisma (divine grace/gift), charity (through Latin cāritās, possibly influenced by Greek kháris), Eucharist (eu-kharistía, "good grace," the thanksgiving rite), and the personal name Grace (ultimately from Latin grātia, itself from a related IE root).
The three Graces of Greek mythology (Khárites — Aglaïa, Thalia, Euphrosyne) personified the root's semantic range: beauty, joy, and festivity, all facets of the state of being pleased/desiring.
Latin hortor (to encourage, to urge) may be related, with the semantic development from "desire" to "urge others toward what is desired," though this connection is debated.
Sanskrit háryati ("he desires, he finds pleasure in") provides the Indo-Iranian reflex, confirming the root's presence in the eastern branches.
The root's survival in both the "yearning" register (English yearn — intense, often melancholic longing) and the "rejoicing" register (Greek khaírein — pleasure, festivity, grace) shows how a single concept of desire can bifurcate: desire fulfilled becomes joy, desire unfulfilled becomes yearning. Both states trace to the same PIE root.