Second in command
14 CFR § 1.1 — Definitions
Official definition — 14 CFR Part 1
REGULATION — OFFICIAL DEFINITIONSecond in command means a pilot who is designated to be second in command of an aircraft during flight time.
Reproduced verbatim from the eCFR. Regulatory definitions control how the term is used throughout 14 CFR.
Is this a regulation?
Yes — this is regulatory text and is legally binding.
Definition published in 14 CFR Part 1. Regulatory definitions are legally binding wherever the defined term is used in 14 CFR.