dial

A dial is a round part you turn to choose a setting, often with numbers or marks. Old phones had a numbered dial you rotated to call someone, and many radios, ovens, and other machines have dials too. Today, we still say we "dial" a number—even if we tap a screen instead of turning anything.

People also use it in common phrases. You can "dial up" the volume or "dial down" the heat, meaning to change it little by little. If someone is "dialed in," they're fully focused. And you can "dial in to" a meeting to join by phone.

The word "dial" first named a marked face or plate that shows (or helps set) a value—like the dial of a clock or watch, or the dial on a gauge. One of the oldest examples is the sundial: the sun's shadow moves across the dial to show the time of day.

Later, the word was used for the circular number wheel on old-fashioned telephones. You put your finger in a hole and rotated the dial to each digit. That physical action gave us the verb: to dial a number, meaning to enter a number and make a call. "She dialed her mother's number while waiting for the bus." You might also hear, "He dialed the operator for help."

"Dial" also works for choosing a setting on equipment, even when nothing is actually round: you can dial the radio to a certain station, or dial the oven to 350°F. And in everyday speech, it often means to adjust something gradually or to the right level. You might "dial up" the excitement (increase it) or "dial down" the tension (decrease it). "The director asked the actor to dial back his performance; it was a bit too intense."

"Dial in" has two common uses, depending on context. You can dial in to a meeting to join remotely, or you can be dialed in, meaning you're completely focused and performing well. Interestingly, the word traces back to the Latin dies, meaning "day," through its link to sundials. So whether you're calling someone, turning a control, or talking about the face of a clock, a dial is all about selecting and adjusting.