By its very nature, vitamin A causes drying of the skin and exfoliation. A bevy of prescription and OTC vitamin A topical preparations make use of this side effect to treat a variety of skin concerns. The term Retinoid refers to any Vitamin A based molecule. It's a category, similar to saying antibiotic. They may be related, but some are stronger and more effective than others.
Pototype sheets for Weld Quality Workmanship Standard. Undercut. Definition: A groove cut at the toe of the weld by the welding arc and left. unfilled. Depth of undercut shall not exceed 1/32.
Word Origin and History for undercut Expand. v. late 14c., to cut down or off, from under + cut (v.). In the commercial sense of to sell at lower prices (or work at lower wages) it is first attested 1884. Figurative sense of render unstable, undermine is recorded from 1955, from earlier literal meaning cut so as to leave the upper portion larger than the lower (1874).