Alizarin

Chemical compound and histologic stain

Alizarin is an organic compound with formula C14H8O4 that has been used throughout history as a red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus. In 1869, it became the first natural dye to be produced synthetically.

This keyword could refer to multiple things. Here are some suggestions: