facet

noun

flat surface of a gem, crystal, etc.
feature of a polytope in the next-lower dimension
unique aspect of a personality trait
the external corneal surface of an ommatidium
a smooth flat circumscribed anatomical surface (as of a bone or tooth)

Wiktionary

Pronunciation: /ˈfæs.ɪt/ / /ˈfas.ɪt/ / /ˈfɛs.ət/

noun

Etymology: Etymology tree Proto-Indo-European *dʰeh₁k- Proto-Indo-European *-yéti Proto-Indo-European *dʰh₁kyéti Proto-Italic *θakjō Proto-Italic *fakjō Late Latin faciō Proto-Italic *-jēs Late Latin -iēs Late Latin faciēs Late Latin facia Old French face Middle French face French face Proto-Indo-European *-tós Proto-Italic *-tosder.? Late Latin -ittus Old French -et Middle French -et French -etder. French -ette French facettebor. English facet Borrowed from French facette.

Any one of the flat surfaces cut into a gem.
“This facet of the diamond was masterfully cut to enhance its value.”
One among many similar or related, yet still distinct things.
“The child's learning disability was only one facet of the problems contributing to his delinquency.”
One of a series of things, such as steps in a project.
“We had just about completed the research facet of the project when the order came to cancel it.”
One member of a compound eye, as found in insects and crustaceans.
A smooth circumscribed surface.
“the articular facet of a bone”
Any of the small joints at each segment of the spine that provide stability and help guide motion
The narrow plane surface between flutings of a column; a fillet.
A face of codimension 1 of a polytope.
A criterion that can be used to sort and filter, such as the colour or size of products in an online store.

verb

To cut a facet into a gemstone.