prolabium pro·la·bi·um (prō-lā'bē-əm)
The exposed part of the lip, especially the small elevation at the termination of the philtrum.
The central portion or prolabium is usually smaller than normal, and is closely adherent to the os incisivum.
In aggravated cases, the os incisivum and prolabium are adherent to the end of the nose.
With regard to the most delicate part of the operation, the management of the prolabium.