Philtrum

The philtrum is the vertical groove running from the base of the nose down to the top of the upper lip, bounded by two ridges that meet the lip at the cupid's bow. In facial aesthetics the measurement that matters is its length relative to the rest of the lower face: a short philtrum brings the upper lip closer to the nose and is read as youthful, while a long one lengthens the space between them. Philtrum length increases gradually across adult life as soft tissue descends, which is part of why it is discussed as an age marker. It cannot be changed by anything non-surgical — the procedures that shorten it are surgical lip lifts — and it is measured from a front-facing photograph reliably, unlike most of the profile measurements in this glossary.