Eye liner is a makeup product that is used to enhance the eyes and create definition around them. There are various different names for eye liner that can be used interchangeably. Some common synonyms for eye liner include kohl, pencil liner, liquid liner, gel liner, and marker liner. Kohl is a traditional form of eyeliner that is made from a mixture of soot and other natural ingredients, while pencil liner is a classic type of liner that can be used for precise application. Liquid liner and gel liner are more modern types of liquid eyeliner that can create bold lines, while marker liner is a newer type of liner that resembles a felt-tip pen. Whatever name you use for this makeup product, it remains a popular tool for achieving a dramatic or natural eye makeup look.