Definition
The minimum weather conditions — typically expressed as visibility, and sometimes ceiling — required to legally and safely depart an airport on an instrument flight rules (IFR) flight. Departure minima may be the standard values published in the regulations, or higher non-standard values established for a specific runway when terrain, obstacles, or other hazards require them.
Plain English
The lowest weather you're allowed to take off in when flying IFR. If the visibility (and sometimes the cloud height) is worse than the published number, you can't legally depart from that runway.
Context Anchor
Seen in instrument departure planning, especially in the Takeoff Minimums and Departure Procedures section for an airport or heliport.
Derivation
Departure' comes from the Old French desparter, meaning to leave or go away. 'Minima' is the Latin plural of minimum, meaning the smallest amount. Together: the smallest acceptable conditions for leaving the ground.
Why Pilots Care
Determines whether a safe IFR departure is possible in given weather and directly affects go/no-go decisions.
Intuition Check
Do not read minima as a comfort level or a personal safety margin. In this context, departure minima are specific published weather limits for starting the departure.
Example Sentence 1
The pilot checked the departure minima for runway 27 and found that one-mile visibility was required before they could legally take off.
Example Sentence 2
Low visibility kept the helicopter on the ground because conditions were below the published departure minima.