noun

1. an image of a god, used as an object or instrument of worship
2. in monotheistic belief, any heathen deity
3. any object of ardent or excessive devotion or admiration
4. a false notion or idea that causes errors in thinking or reasoning
5. Archaic anything that has no substance but can be seen, as an image in a mirror
6. Obsolete
   1. any image or effigy
   2. an impostor

Etymology: ME idole < OFr < L idolum, an image, form, specter, apparition (in LL(Ec), idol) < Gr eidōlon, an image, phantom (in LGr(Ec), idol) < eidos, form: see -oid