Tapetum

‖Ta‐pe″tum (?), n. [NL., from L. tapete a carpet, a tapestry.] (Anat.) An area in the pigmented layer of the choroid coat of the eye in many animals, which has an iridescent or metallic luster and helps to make the eye visible in the dark. Sometimes applied to the whole layer of pigmented epithelium of the choroid.