Fuel
Middle English: from Old French fouaille, based on Latin focus ‘hearth’ (in late Latin ‘fire’).
wiktionary
From Middle English fewell, from Old French fouaille, feuaille, from feu(“fire”). Cognate with Spanish fuego(“fire”).
etymonline
fuel (n.)
c. 1200, feuel, feul "fuel, material for burning," also figurative, from Old French foaille "fuel for heating," from Medieval Latin legal term focalia "right to demand material for making fire, right of cutting fuel," from classical Latin focalia "brushwood for fuel," from neuter plural of Latin focalis "pertaining to a hearth," from focus "hearth, fireplace" (see focus (n.)). Figurative use from 1570s. Of food, as fuel for the body, 1876. As "combustible liquid for an internal combustion engine" from 1886. A French derivative is fouailler "woodyard." Fuel-oil is from 1882.
fuel (v.)
1590s, "feed or furnish with fuel," literal and figurative, from fuel (n.). Intransitive sense "to get fuel" (originally firewood) is from 1880. Related: Fueled; fueling.
