In 1970 Dmitri Borgmann and Dwight Ripley compiled a list of “missing words” — foreign words with complex or interesting meanings that have no counterparts in English. I can’t immediately confirm most of these, but they’d certainly be useful words:
DENTERA (Spanish): a setting of the teeth on edge
PAPABILE (Italian): having some chance of becoming Pope
PIECDZIESIECIORUBLOWY (Polish): costing fifty rubles
PREDSVATEBNY (Czech): taking place on the eve of a wedding
KWELDER (Dutch): land on the outside of a dike
EZERNYOLCSZAZNEGYVENNYOLCBAN (Hungarian): in 1848
PASAULVESTURISKS (Lettish): of worldwide significance
MIHRAP (Turkish): a woman still beautiful though no longer young
UBAC (Provençal): the sunless north side of a mountain
HARFENDAZ (Turkish): one who makes insulting remarks to women in the street
PENCELESMEK (Turkish): to lock fingers with another and have a test of strength
MEZABRALIS (Lettish): a revolutionary hiding in a forest
MATAO (Brazilian Portuguese): a jockey who crowds the others against the fence
NEMIMI (Japanese): the ears of one sleeping
YOKOTOJI (Japanese): bound so as to be broader than long — said of a book
TOADEIRA (Portuguese): a harpooned whale that continues to sound
In 2006 the Goethe Institute held a competition to find German words that deserve a place in English. The winner was Fachidiot, literally “subject idiot,” a scholar blinkered by long study: “A one-track specialist still notices what is going on around him in the world which has nothing to do with university. A Fachidiot simply does not, or not anymore.” Runners-up included Backpfeifengesicht, “a face which invites you to slap it”; Kummerspeck (literally, “grief bacon”), “excessive weight gain caused by emotion-related overeating”; and Torschlusspanik (“gate closing panic”), the fear that time is running out to act.
(Dmitri Borgmann, “Missing Words,” Word Ways 3:1, February 1970.)