Is labrum a word in the Scrabble Dictionary

Yes, labrum is playable

...and is worth 14 points.

Found in the following dictionaries

Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)

"Labrum" Definition

noun

A lip or liplike structure, such as the one forming the roof of the mouth in insects.
The outer margin of the opening of a gastropod shell.
An upper or anterior mouthpart of an arthropod consisting of a single median piece in front of or above the mandibles.
A ring of fibrous cartilage forming the margin of the shallow cavity of the upper part of the scapula by which the humerus articulates with the pectoral girdle.