Someone who practices, works toward, and believes in being great.
Mary chose whole wheat over white bread 'cause she's trying to be her greatist.

Paul's a greatist. Reads The Greatist Blog every day.
by arealperson8 April 23, 2011
A euphemism usually used for a crappy game brought down to 20 dollars to attract more sales.
Where FInal Fantasy X and Legend of Zelda are, DBZ Bukodai and John Madden's fishing are not greatists hits.
by DesPERRYado January 28, 2005