In Spanish, the expression "No hay tu tía" roughly means that there's no way to do something.
However, "tía" on its own means "aunt", and "there's no aunt of yours" is kind of a... weird? way to express such a concept.
The DLE entry for "tía" says nothing about this saying or meaning, hence my question: where does "No hay tu tía" come from, and how did it end up with that meaning?
You won't find that in the DLE under tía, but under tutía. The tutía or atutía was a healing salve used in ancient times, so no hay tutía means there is no remedy for that. Of course, tutía came in disuse long time ago, so nowadays nobody remembers it and the idiom evolved into no hay tu tía, which is quite meaningless, but at least uses familiar words.
It is a very popular and common misunderstanding. The word originally was tutía or atutía:
Del ár. hisp. attutíyya, este del ár. clás. tūtiyā['], y este del sánscr. tuttha.
- f. Óxido de cinc, generalmente impurificado con otras sales metálicas, que, a modo de costra dura y de color gris, se adhiere a los conductos y chimeneas de los hornos donde se tratan minerales de cinc o se fabrica latón.
- f. Ungüento medicinal hecho con atutía.
The expression has its origins in the shortened form tutía, as is stated by the DLE itself:
no hay tutía
Tb. no hay tu tía.La var. no hay tu tía, falsa separación de no hay tutía, en ambos casos con el sentido figurado de 'no hay remedio', porque la tutía se empleaba con fines medicinales.
- expr. coloq. U. para dar a entender a alguien que no debe tener esperanza de conseguir lo que desea o de evitar lo que teme.
The funny thing is that the expression soon came to be expressed as tu tía. There is only one case in the CORDE with tutía, in the form "no hubo tutía", dating from 1870. But there are several cases with tu tía, ranging from 1797 to the 20th century.
The reason for that is that the tutía remedy was obsolete from the very beginnings of the saying. Texts with the word tutia or tutía can be found in the CORDE from the 13th to the 17th centuries, but not after that date:
Del segundo grado del signo de capricornio es la piedra a que dizen tutia uerde que es llamada marina Et la minera desta es en ribera de la mar de tierra de cin. [...] Del tercero grado del signo de capricornio es la piedra de la tutia amariella a que llaman espannola.
Alfonso X, "Lapidario", c 1250 (Spain).
Quando ya las viruelas están desecadas, para que se acaven de caer y quitar, se usará del azeyte rosado o del ungüento rosado, y si uviere algo que abajar o emparejar en las voquillas y llagas, mézclese con esto dicho el ungüento blanco y litargirio, y si se usare del azeyte violado y rosado con polvos de litargirio y tutia preparada, con un poco de alcanphor y alvayalde, con el buen discurso del médico y conforme a la disposición del paciente, creo hará maravillosos effectos y acabará de derribar las viruelas, y emparejará el rostro quitando los hoyos y señales que tuviere.
Manuel de Escobar, "Tratado de la esencia, causa y curación de los bubones y carbuncos pestilentes", 1600 (Spain).
To complete Gorpik's and Charlie's excellent answers, let's check what Google Ngram Viewer shows upon searching for both:
As you can see, the version of tu tía (blue) has gotten more hits over the years and now it is the one commonly used (despite a little peak of tutía out of late).
This reminds me about the expression motu proprio, which is usually and wrongly written as (de) motu propio (Fundéu reported it) and the graph shows how they are nowadays used equally.
