Someone who gives the impression of placing material things above people.
However, this is usually used by people who feel inferior to someone who has nicer clothes, better shoes, etc. than themself. So they use this word to try to lift themselves out of their dark, sad hole.
Ashley: Wow, I really love those shoes Jen's wearing... & Her shirt is really cute too.
Amanda: Pshh, she's so materialistic. At least I have.. Friends...