The Ultimate Lash Extension Glossary: Terms Every Client Should Know
Last updated: July 2026 | Reading time: 8 minutes
The lash extension world has its own vocabulary, and it can be confusing if you are a client trying to understand what your lash artist is talking about — or a new artist learning the profession. This glossary covers the most important terms you will encounter.
Extension Types
Classic extensions: One synthetic extension bonded to one natural lash. The most natural-looking option. Also called 1:1 or one-to-one.
Volume extensions: Multiple ultra-fine extensions formed into a fan and bonded to one natural lash. Creates more fullness and density than classic. Fans can be 2D (two extensions) to 6D (six extensions).
Mega volume: Fans of 6 to 16 ultra-fine extensions per natural lash. Maximum density and drama.
Hybrid extensions: A mix of classic individual extensions and volume fans applied across the lash line. Creates dimension and texture — more than classic, less uniform than full volume.
Russian volume: Volume technique using handmade fans, named for its origin in Russia. The artist creates each fan by hand during the appointment.
Wispy lashes: A style that mixes different lengths and some "spike" lashes for a textured, effortlessly glamorous look. Very popular on social media.
Curl Types
B-curl: A subtle, natural curve. Mimics naturally curly lashes. Rarely used as a primary curl in extensions.
C-curl: The most popular curl. A noticeable curve that opens the eye without being extreme. Works for most eye shapes.
CC-curl: Slightly curlier than C. A good middle ground for clients who want more lift without jumping to D.
D-curl: A strong, dramatic curl. Stands up noticeably from the lash line. Excellent for hooded eyes or clients wanting a doll-eye effect.
L-curl: Has a flat base with a sharp upward curve. Designed specifically for clients with very straight natural lashes or monolid eye shapes.
L+-curl: A variation of L-curl with a slightly more gradual curve. Bridges the gap between L and D.
M-curl: A newer curl type with a moderate lift and a slight pinch at the base. Works well on downturned eyes.
Materials and Measurements
Diameter (thickness): Measured in millimeters. Common sizes: 0.03mm (mega volume), 0.05mm (volume), 0.07mm (light volume/hybrid), 0.10mm, 0.12mm, 0.15mm (classic). Thinner diameters weigh less and allow for more extensions per fan.
Length: Measured in millimeters, typically ranging from 8mm to 16mm. Most clients wear 9mm–13mm. Longer lengths are used sparingly for dramatic effect.
Faux mink: The most common extension material. Synthetic fibers that mimic the softness of real mink. Lightweight, consistent, and cruelty-free.
Silk: A slightly glossier, shinier fiber. Some clients prefer the extra sheen.
Flat lashes (cashmere/ellipse): Extensions with an oval cross-section instead of round. They appear darker and fuller while weighing less. Popular for classic sets.
Adhesive and Application
Cyanoacrylate: The main chemical compound in lash adhesive. Medical-grade versions are used for lash extensions. This is also what some people are allergic to.
Cure time: The time adhesive takes to fully harden. Typically 24 hours for full cure, though initial setting happens in 1–2 seconds.
Isolation: The process of separating one natural lash from all its neighbors before applying an extension. Proper isolation is the most important safety element in lash extensions.
Stickies: When two or more natural lashes are accidentally glued together. This causes pulling, discomfort, and potential damage. A sign of poor technique.
Bond: The adhesive connection between the extension and the natural lash. A good bond wraps around the natural lash for 360-degree contact.
Retention: How long extensions stay attached before falling out with the natural lash. Good retention means 3–4 weeks of wear.
Lash Maps and Styles
Lash map: The planned layout of extensions across the lash line — specifying which lengths, curls, and thicknesses go where. Custom maps are designed for each client's eye shape.
Cat-eye: A lash map where the longest extensions are at the outer corners, creating an elongated, lifted effect.
Doll-eye: The longest extensions are at the center of the eye, creating a wide, open-eyed effect.
Natural/open-eye: A balanced map that follows the natural lash growth pattern. No dramatic emphasis on any area.
Kim K lashes: A style combining volume with some very long spike lashes for a textured, editorial look.
Wet look: Extensions that appear slightly separated and defined, mimicking the look of wet or freshly coated lashes.
Maintenance Terms
Fill (refill/infill): A maintenance appointment to replace shed extensions and refresh the set.
Full set: A complete application of extensions across all suitable natural lashes.
Lash bath/lash wash: The process of cleaning extensions with a foam cleanser.
Spoolie: A small brush used to groom and separate extensions. Use daily.
Lash sealant: A coating applied over extensions to protect the adhesive bond and prolong retention.