| Safe: | Free from danger of being hit |
| Safe Play: | A strategy that leaves no blots, or a strategy that leaves blots only in positions where the opponent is unlikely to hit |
| Safety a stone: | To move a stone out of danger of being hit |
| Safety Up: | Cover a blot or move it out of range of being hit |
| Sandbag: | To conceal or misrepresent your true ability or to enter a tournament division below your skill level |
| Save a Number: | To leave a position in which a particular number will play comfortably next turn so you will not be forced you to destroy your position if you roll that number |
| Secure a Point: | Cover a blot |
| Semifinalist: | One of the four players competing in the semifinals of an elimination tournament |
| Semifinals: | The second-last round of an elimination tournament; the one that determines the two players who advance to the finals |
| Settlement: | A decision to end a game early with the payment of points by one player to the other based on the agreed fair value of the position |
| Shark: | A good player who seeks out weaker players and persuades them to play for high stakes |
| Shift Gears: | Change game plan |
| Shift Points: | To give up one point in order to make an adjacent point |
| Shot: | An opportunity to hit an opponents blot |
| Simple Direct Shot: | a blot within range of being hit with a single number |
| Single Elimination: | a tournament format in which each competitor continues playing until he loses |
| Single Game: | A completed game for which the result is not a gammon or a backgammon |
| Single Shot: | One blot which can be directly hit in only one way |
| Slot: | To place a single stone on a point you wish to make |
| Slot and Split: | To slot a stone in your own home board while your runners are split |
| Small Play: | a safe play when a bolder, more aggressive play is available |
| Solid Prime: | a prime with no gaps; a full prime |
| Split: | To separate two stones which are together on a point and leave them as blots |
| Squeeze: | To take advantage of the opponents requirement to make a move which will be disadvantageous for him |
| Stack: | Four or more stones piled on a point |
| Stakes: | The amount wagered by the participants in a game of backgammon per point |
| Stay Back: | To remain in the opponents home board |
| Stay Off: | Fail to enter from the bar |
| Stay Out: | Fail to enter from the bar |
| Steam: | To play wildly, out of annoyance or impatience at ones bad luck. To lose ones emotional stability in a gambling context; To take bigger and bigger risks in an effort to recoup earlier losses |
| Steamer: | One who steams |
| Stone: | Checker,piece, man |
| Straight Race: | Pure race |
| Stretched: | a position barren of spare stones or builders |
| Strip a Point: | To remove all but two stones from a point |
| Stripped: | Stretched |
| Strong Board: | a home board with several anchors |
| Suicide Play: | To purposely leave a blot to be hit so it can be recirculated. Also known as a Hara-Kiri play |
| Swiss-Cheese Formation: | a position with many gaps and few adjacent anchors |
| Sympathy Flight: | Consolation flight |
