Definition
The lowest altitude and, where applicable, the lowest visibility (or runway visual range) at which a pilot is permitted to continue an instrument approach toward landing. If the required visual references are not in sight at the published minimum altitude, the pilot must execute a missed approach.
Plain English
The point on an instrument approach where you must be able to see the runway environment to keep going. If you can't see it by then, you have to go around.
Context Anchor
You see approach minima on instrument approach charts and use them during the approach briefing and final decision to land or miss the approach.
Derivation
From 'approach' (the procedure flown to align with and descend toward the runway) and 'minima' (Latin plural of minimum, meaning the lowest allowable values). Together: the lowest values of altitude and visibility allowed during the approach.
Why Pilots Care
These limits protect against controlled flight into terrain and ensure enough visual cues exist to complete the landing safely.
Intuition Check
Do not read minima as a goal or a suggestion. In this context, approach minima are the published lower limits for that instrument approach.
Example Sentence 1
We briefed the approach minima before starting the descent so both pilots knew the decision altitude and required visibility.
Example Sentence 2
Because the reported visibility was below approach minima, the crew began the missed approach procedure at the final approach fix.