From Longman Dictionary of Contemporary Englishhighlighterhigh‧light‧er /ˈhaɪlaɪtə $ -ər/ noun [countable] 
TZa special light-coloured pen used for marking words in a book, article etc
TZa special light-coloured pen used for marking words in a book, article etcExamples from the Corpus
highlighter• This will act as a highlighter, making your eyes look bigger and brighter.• So you have to make eight copies and then go through with a highlighter, one on each one.• To the rest of the eyelid, apply peachy, bronze highlighter.• Blend away any creases in your make-up and gently apply the new eyeshadow, highlighter and pencil, the blusher and lipstick.• Apply slightly lighter highlighter on the remaining two-thirds of the eye - I prefer something with a little sparkle.• Blend where the highlighter joins the socket shadow and outer third of the eyelid. 