introuvable adjective impossible to find; "the book is practically introuvable".
Two questions: What is the etymology of this word? Is there another, less obscure word for "unfindable" ?
Edit: Must be somehow connected to (treasure)
trove.
ORIGIN late Middle English : from Anglo-Norman French tresor trove, literally ‘found treasure.’
(Treasure) trove is from Anglo-Norman tresor trove, the second half of the phrase is from trover 'to compose, invent, find' (it's also a legal term in English). It might be from Old Provencal trobar (which yields troubador) which in turn is usually connected with Vulgar Latin tropo (tropare) from Latin tropus 'song' from Greek τροπος (tropos) 'figure of speech, (lit.) turn' (from τρεπειν (trpein 'to turn', cf. apotropaic, heliotrope, entropy). Latin inventio from invenio (invenire) 'to find, (lit.) come upon'.
Unfindable, undiscoverable; spec. of books. Also as n. [OED2]
actually a French word, I think the English word more commonly used by American booksellers is, well, unfindable.
in other contexts, perhaps unattainable.
-joe (introvenient) friday
Trouver is "to find", in French.
Some terms I can think of are: lost; secreted away; gone for good; and too well hidden. Or, in tsuwm's bookseller-type sense, perhaps "unlocatable"; "untraceable".