Update: This word was added to the dictionary in October 2021
Born* in a Vine video on June 21, 2014, the term fleek is a busy word. It was originally (and still is most commonly) applied to perfectly-groomed eyebrows, but the word has been used to describe everything from hash browns to skateboards.
(*"Born" isn't quite true; there's some earlier evidence of the term in use, but not with the meaning that's caught on.)
Fleek does usually appear in the phrase on fleek. Like the phrase on point, it's used to mean basically "perfectly done" or "exactly right." Here it is, out in the wild ("wild" here being "Twitter"):
Everything on Fleek, fleek, fleek fleek 🎶🎵
— G-WDGF (@GUNNMAN38LF) October 9, 2017https://twitter.com/ClaClaMK/status/814246983795871748
And applying to those beautiful brows:
Eyebrows on fleek
— Dominic Trippett (@DomTrippett) May 31, 2017
Yep, looks like fleek is still on fleek. In fact, "on fleek" was nominated by the American Dialect Society for its 2015 "Word of the Year" in the "Most Likely to Succeed" category.