AAV - Average Auction Value. This is the average amount a player is currently going for in auction drafts.
ADP - Average Draft Pick. This is the average pick a player is being drafted at.
ARV (or VAR) - Above Replacement Value. This is a tool emphasizing the points a user can gain by drafting a certain position rather than waiting to pick a player from that same position via waiver wire.
Core - This is the nucleus of the starting lineup plus one RB and one WR. For example, say your league's starters are: 1 QB, 2 RB, 2WR, 1 TE, Flex, 1 K, 1 DEF. The core will be consisted of: 1 QB, 3 RB, 3 WR, 1 Flex, 1 TE.
Draft Value - this is an analytical tool that shows the user points they will gain by taking a player for each respective position compared to waiting 2+ rounds.
VBD - Value Based Drafting. This is a value given to every player that compares a player's projected fantasy points to the projected fantasy points of other players at his same position.