Terminology

 Crème
This is probably the most popular finish. It’s a solid smooth color, with no special effects like shimmer, glitter, etc. It has a fairly glossy finish with keeps it from being matte or satin, but can sometimes have almost a dusty finish where it seems a bit buffed out. Not enough to change the finish from a Crème though. (Revlon Nail Enamel in “Minted”)


Shimmer
This is up there with most popular finish. Shimmers have tiny particles in them which give them their “shimmering” finish. They’re different from glitters, because there aren’t obvious glitter chunks in the polish and they’re more uniformed in distribution. (Sally Hansen X-Treme Wear in “The Real Teal”)
Frost (Pearl/Satin)
Unlike the shimmer finish, frost polishes have a pearlescent sheen to it without obvious shimmer particles. Because of their formula, more particles that color, they tend to be thicker and leave some brush strokes behind. I’ve seen people distinguish between Frost, Pearl and even Satin finishes, but for me they really don’t seem different enough to be their own categories. Pearl, for me, is a specification for white or light pink based shimmers/frost.  (Sally Hansen X-Treme Wear in “Gunmetal”)
Sheer
If you have a Visible Nail Line (VNL) then you have a sheer finish. These come in all sorts of colors and finishes. It’s a distinction between opacity, not color. (Essie in "Limo-Scene")

Duochrome
This finish gives off a dual color shine. As you move your nail side to side, the color of the polish will change. It’s very distinct and more drastic than an iridescent finish.  These are typically shimmers from what I’ve seen. (Sinful Colors in “Shausha”)
 
Iridescent
Unlike a duochrome, iridescent have a more discrete color change. It’s more angle and light depended to appear a different color than with a duochrome. These tend to be fairly sheer which makes them great for layering to jazz up a solid crème polish. (Sally Hansen X-Treme Wear in “Lime Lights”)
 

Metallic (Chrome)

This is pretty similar to frost finishes as far as their consistency and look goes, but metallics are more distinguished by their colors. They have metal based colors that are very reflective. They come in a variety of colors, but silver and gold are the most common metallic/metal colors.  These are incredibly similar to the Foil finish. Foils are just smoother and come in non-metal based colors. (Sally Hansen Color Quick Chrome Pen in “Silver Chrome”)

Matte
This is a muted finish distinguished by its nonglossy sheen. Matte’s aren’t necessarily dull. A good Matte will still have a lot of depth and body to its color. It’s not supposed to be just a shine that was rundown. Mattes are similar to Suede’s, but Suede’s, to me, have a more dusty than dull finish. (Sinful Colors in "Black on Black"topped w. Essie in "Matte About You")
Glitter
Glitters is the umbrella word for polishes that have glitter chunks in them. There are different sizes and classes of glitter such as; Microglitter (super fine ground up particles); Marcoglitter (large very visbale chunks of glitters); String (Rectangle stream shaped pieces of glitter); Flakie (Large particles with no particular shape)  . Some will be very opaque and have full coverage on their own while others are better used as a top coat. (Hot Topic's Unnamed Red Glitter)

Holographic (Holo)Holographic polishes are micro-glitters that have a rainbow effect with the glitter particles. Some even give off a “3D” quality, particular  in photos. There are liner holo’s which will give lines of color very similar in the way you would see a rainbow. Then there are shattered holo’s which will give all different particles of colors all over the nail. (Milani 3D Holographic in "HD")

Blackened _____ (Vamp/Almost Black)
These colors are so dark they’re almost black. So you would say you have a Blackened Green or a Blackened Purple, etc. Vamps tends to be reserved for those dark blood red colors.

 
Franken (Frankie)
These are those amazing homemade nail polish creations. FRANKENstein should be ringing a bell right now. Mix colors, glitters, holos and bamn… you have your very own Frankie.

Dupe (Duplicates)
Sometimes a red is a red is a red, but sometimes a nail polish has something spectacular about it and someone else noticed! There are the polishes that are so similar they look like duplicates and can be swapped with one another. It’s like a knock off. Typically you would find a duplicate for an expensive, limited or retired polish.  

The Louboutin Manicure
This is when you paint the underside of your nails a different color than what you paint your actual nail. This is a look reserved for those lucky people who can grow their nails long enough to actually even accomplish this manicure. I love black nails with a red underside. It’s so Elvira to me, whom I love.

Shatter (Crackle)
These polishes do what their name suggests. They shatter and they crackle! It’s a polish that you use as an overcoat to another polish. The polish will Shatter over its base polish and then you can see it coming through the cracks. These polishes typically crack along with your brush stroke. If you paint vertical strokes they’ll crack vertical. Horizontal strokes horizontal cracks. Diagonal strokes diagonal cracks. All over strokes all over cracks!