1D Explained

1D, 1-D, or 1d can refer to:

Alpha-1D adrenergic receptor
Astra 1D, a satellite
Canon EOS-1D, Canon's first professional digital camera
Long March 1D, a satellite
One-dimensional space in physics and mathematics
One Direction, an English-Irish boy band
Penny (British pre-decimal coin), routinely abbreviated 1d.
1D, the hexadecimal code for the Group Separator control character

See also