The adverb: doing something in a materialistic way — choosing, judging, or living as if money and possessions were the main thing that counts. Same disapproval as materialistic. You might say someone measures success materialistically, or talks materialistically about a job (salary first, meaning never). It is a long, rather stiff word. In speech people more often say “in a materialistic way,” or they just use the adjective. You will see this form more in careful writing than in chat.