1. noun /sæn.sɛɹɪf,sænz.sɛɹɪf/
A typeface in which the characters do not have serifs.
2. adjective /sæn.sɛɹɪf,sænz.sɛɹɪf/
Of a typeface, without serifs.
If you have some sans-serif fonts on your computer, you can play this game, too.
Wikipedia foundation.