faltarle un tornillo

== Spanish == === Etymology === Literally, “be missing a screw”. === Verb === faltarle un tornillo (first-person singular present le falto un tornillo, first-person singular preterite le falté un tornillo, past participle le faltado un tornillo) (idiomatic) to have a screw loose === Further reading === “faltarle a alguien un tornillo, o tener flojos los tornillos”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025