Definitions for "mentum"
a projection like a chin formed by the sepals and base of the column in some orchids
a projection below the mouth of certain mollusks that resembles a chin
in Orchidaceae, a spur formed by extension of the base of the column.
A labial sclerite articulating basally with the submentum and apically with the prementum; often fused with the latter and indistinguishable as separate sclerite.
Keywords:  labium, ventral, median, plate, insects
The front median plate of the labium in insects. See Labium.
A ventral plate on the ventral side of the head.
Keywords:  protruding, jaw, lower, part
the protruding part of the lower jaw