Beauty Glossary: L

Lactic acid - alpha-hydroxy acid derived from milk.

Laminaria - green alga, rich in iodine, which is used in algotherapy.

Lanolin- a fatty secretion derived from sheep's wool. It's completely natural and easily absorbed by the skin but can cause allergic reactions and clog pores. It tends to be heavy, sticky, and greasy.

Lanolin alcohol - an emollient alcohol.

Lavender - the leaves, flowers, and oil from this plant are used in moisturizers, and hair care and body care products. It's an antiseptic, helps clear acne, and soothes the skin.

Lecithin - an emulsifier used in lotions and creams.

Linoleic acid (aka Vitamin F) - an essential fatty acid that prevents skin dryness and roughness.

Lipid barrier replacement - when the lipids that hold skin cells together in the stratum corneum get poked full of holes, water evaporates and results in dryness and sensitivity. Lipid barrier replacements such as ceramides can help re-mortar the wall.

Liposomes - tiny lipid (fat) balls that deliver moisture to the skin. Because of their small molecular size, they are able to penetrate the cell wall reasonably well and are used in moisturizers.

Loofah - the skeleton of a gourd plant that's used as an exfoliating tool in the bath or shower.

Lowlights - darker tones subtly laid into small sections of the hair.

Lubricant - an oil, cream, or other ingredient that moistens and softens skin.

Lye - a caustic ingredient (sodium hydroxide) used in hair relaxers and soaps.