noun, feminine/fɛ̃ d(ə) lu/
ravenous hunger
“avoir une faim de loup” — to be hungry as a hog, to be very hungry, ravenous; to be so hungry one could eat a horse
Literally, “hunger of a wolf”. Compare Italian fame da lupo, Romanian foame de lup, Russian во́лчий аппети́т (vólčij appetít).