Definitions for "Two Pair"
Keywords:  singleton, kicker, poker, pair, rank
You have Q, 10 and the flop comes Q, 10, 3. You have the top 2 pair. Or, You hold Q,10 and the flop comes Q, 3, 3. You still have two pair but everyone else has at least a pair of threes since they are community or board cards.
A hand consisting of two cards of one rank, and two cards of another rank (and an unpaired card). AA883 is two pair, sometimes also called aces up. Wise guys often describe their quads as two pair. "Let's see, I got a pair of tens and... another pair of tens." Bad things happen to wise guys.
A hand with two separate pairs or cards with the same rank.