Billie Eilish's synaesthesia inspired her debut fragrance.

Billie Eilish

Billie Eilish

The 19-year-old pop superstar has the condition - a perceptual phenomenon that connects sensory or cognitive pathways - and she has revealed how, peculiarly, everything she does has to "sound like a certain smell".

She told WWD of scent: “It’s involved in every ounce of my life, and in everything I do.

“Every choice I make, fashion-wise, hair-wise and musically, I always want things to sound like a certain smell.

“I have a very, very, very strong and long relationship with scent.”

The 'bad guy' hitmaker wanted the fragrance, which is simply titled Eilish, to be "mentally sexy" and to create a sense of intimacy between the wearer and those who can smell the scent on them.

She told Allure: "I've always been infatuated by necks and collarbones and back muscles and shoulders and armpits. I've always thought they were really beautiful.

"I wanted to accentuate that beauty without making it about [sexualising bodies].

"It's not really supposed to be physically sexy. It's almost supposed to be mentally sexy."

Billie admitted she "almost cried" when fragrance development company Parlux sent her a sample for the Vegan and cruelty-free perfume because it was exactly what she wanted.

She said: "I described in detail what it is that I wanted, what I loved idea-wise about it, how I wanted it to feel, the kind of warmth that I wanted it to have, and the memories that I have in the vanilla world.

"When they first sent me the sample to smell, I almost cried because it was so perfect. It was wild."

The metallic gold bottle is a miniature bust sculpture, with the head cut off above the nose and the detail concentrated around the neck area.

Billie said of the design: "[I want it to be] personal and relatable and intimate. I just want everybody to be able to see themselves in this bottle and see whoever they wanted to see in the bottle."

And the concoction of vanilla, amber, musk, cocoa, rose, and wood was "in her head" for a long time.