- a relief pilot on an airplane
- In commercial aviation, the first officer is the second pilot (sometimes referred to as the "co-pilot") of an aircraft. The first officer is second-in-command of the aircraft, to the captain who is the legal commander. ...
- a relief or assistant pilot of an aircraft; To serve as relief or assistant pilot
- Colchicine versus PEG-INTRON Long-Term Study
- is a person’s friend who has agreed to stay sober and hallucinogenic-free while another youth takes LSD or any other kind of narcotic.