50/50 contest: A contest in which the prize pool is split evenly among the top 50% of the entrants. For example, a game with 50 entrants would have 25 winners. The amount of cash won by each person is slightly lower than double the entry fee, and it depends on the site’s commission. For example, a contest with a $50 entry fee might have a $90 prize.
Auction draft: A player allocation procedure in which team managers bid for players. Managers are given a specific allotment of cash and must build their lineups without exceeding their budgets. Auction drafts are sometimes used in traditional fantasy football leagues; they are generally not used in DFS contests.
Action: Competition in a contest. Players who create head-to-head matchups that are awaiting opponents to join their contests are said to be trying to create or get action, thus increasing the amount of dollars in play for their DFS lineups that week.
Bankroll: The amount of money a DFS player has set aside to wager in contests, such that if he lost that amount, he'd be unable to place any more bets until he finds an outside source of additional cash.
Bearish: A feeling against or not liking a player or contest. For example, the belief that a given player or team may not perform well or that a contest may not offer a very good payout structure. The opposite of “bullish.”
Boom/Bust: A player that has the potential to have a really big performance ("boom") or virtually no contribution ("bust") for the upcoming week. A boom/bust player often projects low despite his potential to post a high score because he’s less likely to boom than bust.