Petrichor

From Tardis Wiki, the free Doctor Who reference
Amy Pond picturing petrichor in her mind. (DW: The Doctor's Wife)
An advertisment for Petrichor perfume. (DW: Closing Time)

Petrichor was, as defined by Idris, the smell of dust after rain. Idris used the word "Petrichor" as part of the key to open a back-up TARDIS control, which she gave to Rory through a telepathic link. (DW: The Doctor's Wife)

Petrichor was also the name of a fragrance company that Amy Pond worked for as a model. Its slogan was "For the girl who's tired of waiting." This modelling job with Petrichor apparently made her rather famous. (DW: Closing Time)

Petrichor