Domino, a word that reminds us of cause and effect, is a perfect fit for a character who appreciates the gravity of every decision and action. In fiction, the domino effect occurs when one small event has a huge impact on another. In real life, a hospital patient who picks up an infection while receiving care can have a similar effect—each new or worsening infection can cause the next medical professional to forget to wash their hands, leading to more infections for the patient and others in the facility. This is a domino effect, and it’s why we often see the phrase, “a domino effect.”

Domino is also a name that suggests a masterful commander who thinks two steps ahead of his or her troops. A domino who knows what might happen will plan accordingly, which can save lives and prevent unnecessary suffering.

A domino is a flat, thumb-sized rectangular block, each face of which is blank or bears an arrangement of spots resembling those on dice. A set of 28 such tiles forms a complete domino. The word is also used for a game played with such pieces, typically by arranging them edge to edge and stacking them in lines or angular patterns. A domino is also used as a playing piece or a building block in structures such as 3-D towers.

The origin of the word is obscure. The word appears to have been borrowed from French around 1750, where it originally denoted a long hooded cloak worn with a mask during carnival season or at a masquerade. The playing piece came later, and it is suggested that the black domino contrasting with a white surplice reminded people of the garment.

There are many types of domino games, but the most popular are blocking games and scoring games. In blocking games, the dominoes are arranged on a table so that one side of a piece is faced up and the other is facing down. Each player draws a number of pieces, and the first player to play his or her domino (typically by touching it to an adjacent one) leads the sequence. When all the tiles are played, the player with the fewest pips wins.

In scoring games, players place the dominoes edge to edge in a row or pattern. They then mark all the points (called pips) on each piece, and count the numbers. Then, each player plays a domino in turn that adds to the total, forming a chain reaction that continues until one domino cannot be placed without disturbing the remainder of the set. These chains can be incredibly complex, and some domino players create artful curved lines, grids that form pictures when the pieces fall, or even 3-D structures like towers and pyramids. Some even create intricate track systems for cars and trains, with the dominoes arranged to make their vehicles travel over or around them in interesting ways. A popular example is the domino track used for the popular TV show, The Amazing Race.