Made hands

Flush

Nut, second nut, third nut, and weak flush

There is a difference between an ace high flush and the nut flush. On Ac7c6c3h1d, if you have JcTc, you have an ace high flush because the best five card hand you can make is AcJcTc7c6c, but you don't have the nut flush. If you had the Kc, you'd have the nut flush. The Qc would thus be the second nut flush, Jc is the third nut flush, and anything less would just be considered a "weak flush".

Note that the nut flush could range all the way down to an eight high flush. On KcQcJcTc2h, the 8c is the highest card you can have that makes a flush. Ac makes a royal flush and 9c makes a straight flush. Similarly, the second nut flush can range all the way down to a seven high, and the third nut flush can range all the way down to a six high.

As you can see from the above example, potential royal and straight flushes will "push down" the nut levels.

Using two hole cards vs. using one hole card

Basic examples:

Using two hole cards: Ac4c on Kc9c3s7cJh
Using one hole card: Ac4d on Kc9c3s7cJc

Edge cases:

Suppose you have AcKc on JcTc7c6c5h. It wouldn't be considered "using two hole cards" even though the best 5 card hand (AcKcJcTc7c) uses two of your hole cards (AcKc). Why? Well, imagine that you had Ac2c instead of AcKc. Now you don't have the Kc as your second kicker anymore. But does that matter? No, it doesn't matter. Since you have the Ac, no one else can have an "ace high flush", and so you'll never move on to using the second kicker as a tiebreaker. Which means that you're effectively only using one of your hole cards in making your best five card hand.

Suppose the board is QcJc9c7c5c:

If you have Ac2h, it's considered "using one hole card". Even though there is a flush already on the board, you have the top kicker.
If you have AcKc, it's considered "using one hole card" rather than "using two hole cards" because the second kicker never comes in to play, as eplained above.
If you have 6c4c, it's considered "using one hole card" because your 6c can potentially come in to play as the fifth kicker. For example, you'd beat 3c2c.
If you have 4c2c, it's considered "on board" because your hand is the same hand as the five card hand on the board. Your 4c never comes in to play because there is no such thing as a sixth kicker.

Three of a kind

Set vs. trips

A set is when you make three of a kind with a pocket pair. Eg. 55 on JT5 would make a set. That's why they call it "set mining" when you call with a pocket pair looking to make three of a kind.

Trips is when you make three of a kind when the board is paired (and thus you don't have a pocket pair). Eg. 65 on J55 would make trips.

A set is generally considered to be a stronger hand than trips because it is more concealed. For example, imagine that you flat call the preflop raiser, and the flop comes 997. Since you (most likely) have a lot of hands with nines in your flat calling range, the opponent will be worried that you made three of a kind. But if you have 44 on A94, well, your hand is much more "hidden".

Top vs. second vs. third vs. fourth vs. middle vs. bottom set

Consider a flop of QT8:

QQ = top set
TT = middle set (not second set)
88 = bottom set (not third set)

Consider a board of QT86:

QQ = top set
TT = second set (not middle set)
88 = third set (not middle set)
66 = bottom set (not fourth set)

Consider a board of QT864:

QQ = top set
TT = second set (not middle set)
88 = third set (not middle set)
66 = fourth set (not middle set)
44 = bottom set

Two pair

Using top board card

Examples:

AT on AT872
A8 on AT872
A7 on AT872
A2 on AT872
AT on AT882 because your two pair is aces and tens, not aces and eights

Weak

Examples:

T8 on AT872
T7 on AT872
T2 on AT872
87 on AT872
82 on AT872
72 on AT872
T8 on AT822 because your two pair is tens and eights, not tens and twos

Two pair with a pair on board (subcategory of "Using board card")

Examples:

AK on ATT87
KK on ATT87
A8 on ATT87, because your two pair is aces and tens, not aces and eights
AK on KTT88, because your two pair is kings and tens, not tens and eights
A9 on TT988, because your two pair is tens and nines, not tens and eights
AA on TT883, because your two pair is aces and tens, not tens and eights
99 on TT883, because your two pair is tens and nines, not tens and eights

Two pair on board (subcategory of "Using board card")

Examples:

AK on JTT88
A3 on TT883, because your two pair is tens and eights, not tens and threes
44 on TT883, because your two pair is tens and eights, not tens and fours

Pair

Overpair

When pocket pair rank is larger than the top board card rank. Eg. QQ on J76.

Top pair, top kicker

Eg. AK on K72
Note that the top kicker can get "pushed down". Eg. on AKQ72, the top kicker gets "pushed down" to be a jack, so top pair top kicker is AJ.
Note that when the kicker would complete a straight, it gets "pushed down" even more. Eg. on AKQJ7, a ten would make a straight, so the top kicker is a nine, and top pair top kicker is thus A9.

Good kicker vs. weak kicker

"Good kicker" refers to the second or third best kicker. "Weak kicker" refers to a kicker that is fourth best or worse.
Note that good and weak kickers can get "pushed down", as explained in the top pair, top kicker section.

Pocket pair under top pair

This refers to a pocket pair between the highest and second highest ranks on the board. Eg. on Q72, JJ, TT, 99, and 88 would all be considered pocket pairs under top pair.

Note that on QJ2, there is no available pocket pair under top pair hands (because there is nothing in between a queen and a jack).

Second pair vs. middle pair vs. weak pair

Consider a flop of QT8:

AT = middle pair (not second pair)
99 = weak pair (not middle pair)
A8 = weak pair
77 = weak pair

Consider a board of QT86:

AT = second pair (not middle pair)
99 = weak pair (not middle pair)
A8 = weak pair (not middle pair)
77 = weak pair (not middle pair)
A6 = weak pair
55 = weak pair

Consider a board of QT864:

AT = second pair (not middle pair)
99 = weak pair (not middle pair)
A8 = weak pair (not middle pair)
77 = weak pair (not middle pair)
A6 = weak pair (not middle pair)
55 = weak pair (not middle pair)
A4 = weak pair
33 = weak pair

Draws

Also see https://en.wikipedia.org/wiki/Draw_(poker).

Using at least one hole card

Draws don't count unless you make the draw using at least one of your hole cards. For example, if you have KcJs on Qd8d7d2d, you technically do have a flush draw, but since the flush draw is on the board, so does everyone else, and thus it doesn't count as you having a flush draw.

Flush draw

This refers to a four card flush draw. Eg. Ac4c on QcJc7h.

See Made hands / Flush / Nut, second nut, third nut, and weak flush for the difference between nut, second nut, third nut, and weak flush draws.

Open ended straight draw

Eg. T9 on 872. You can make a straight in each direction - with a jack or a six.

Double gutshot

Eg. J5 on 987. You can make a straight with a ten or a six.

Note that you have eight outs to a straight, just like you do with an open ended straight draw.

Also note that double gut shots are stronger hands than open ended straight draws because they are more concealed.

Gutshot

When you are one card away from a straight (not two). For example:

T9 on 762 (an 8 is your only out to a straight)
A5 on J32 (a 4 is your only out to a straight)

Overcards

Cards that are higher than the top board card. For example:

Two overcards: AK on J73
One overcard: AT on J73

Overcards are a draw in the sense that you are drawing to the made hand of top pair, rather than to a made hand like a flush or straight.

Backdoor draws

A draw where you are two outs away from your made hand. Of course, it is a lot harder to hit two outs than it is to hit one, so backdoor draws are significantly weaker than regular draws.

Examples:

Backdoor flush draw: Ac4c on Qc9h4d (you need two clubs to make a flush)
Backdoor straight draw KQ on J32 (you need two cards to make a straight; AT or T9 will do)