- You may be looking for the perfume.
Petrichor, as defined by the TARDIS Matrix when inhabiting the body of Idris, was the smell of dust after rain. It was used by the TARDIS as part of the password to open a back-up TARDIS control room, which she gave to Rory Williams through a telepathic link. (TV: The Doctor's Wife)
Petrichor was also the name of a fragrance for which Amy Pond posed as a model in an advertisement, the slogan for which was "For the girl who's tired of waiting". An advertisement for Petrichor, which featured a photo of Amy, was displayed in Sanderson & Grainger where the Eleventh Doctor was working in the toy department. (TV: Closing Time)