Definition of "guyliner"

I threaded my way through a crowd of Goths slouching against cars in guyliner and black pants […]

2011, Joanna Pearson, The Rites and Wrongs of Janice Wills, page 29

Trevor looks kind of emo, rail thin, dark hair, guyliner, wears black all the time.

2012, Megan Bostic, Never Eighteen