As nouns the difference between labellum and glabellum
is that labellum is the lower central petal of orchid flowers, usually developed to be showy and attract pollinators while glabellum is (zoology) the median, convex lobe of the head of a trilobite.
labellum
Noun
(en-noun)
The lower central petal of orchid flowers, usually developed to be showy and attract pollinators.
Synonyms
* lip
----
glabellum
English
Noun
(
glabella)
(zoology) The median, convex lobe of the head of a trilobite.
(
Webster 1913)