1D
One Direction
Example
I've had that "What Makes You Beautiful" song by 1D in my head all day.

From left to right: Zayn, Harry, Liam, Louis, and Niall of 1D
Related Slang
A7X | Avenged Sevenfold |
RHCP | Red Hot Chili Peppers |
FFDP | Five Finger Death Punch |
PM5K | Powerman 5000 |
RATM | Rage Against The Machine |
1D is a common way to abbreviate the name of the popular English-Irish pop band, "One Direction." Band members include Niall Horan, Liam Payne, Harry Styles, and Louis Tomlinson. Zayn Malik was an original member but he left in 2015 to start a solo career.