ACID [as-id] What it is: Substances with a pH value less than 7. The opposite of alkaline. VIDEOS RELATED TO THIS TERM LEARN MORE TERMSVISCOSITYUV DESK LAMPC-CURVE STICKSOVAL NAILEPONYCHIUMACRYLATENAIL ART BRUSHESFillFAN BRUSHCOATINGPEDICUREOLIGOMERSVERTICAL OMBRECOVER PINK POWDERACRYLIC NAILSEXTENSIONNAIL FORMABSORPTIONGRITUV GEL PrevNext