Allergen [al-ler-jen] What it is: A substance that causes an allergic reaction in the body. This reaction can be topical or systemic. VIDEOS RELATED TO THIS TERMNail Tip ApplicationMeet the Winner of NTNA Season 7French White Application LEARN MORE TERMSBACKFILLAUTOCLAVEALKALINECUTICLE OILARTIFICIAL NAILUPPER ARCHANTISEPTICGRITABSORPTIONENAMELABRASIVECOLOR FADINGDOTTING TOOLACETONEUV GELNAIL CLIPPERLED LAMPTHREE-WAY SHINERPROXIMAL NAIL FOLDART PALETTE PrevNext