Plain English Meaning
It is how an instructor measures where a learner is at, what they have mastered, and what still needs work, so training can be adjusted accordingly.
Full Definition
In aviation instruction, assessment is the structured process an instructor uses to evaluate a learner's knowledge, skill, judgment, and progress against defined standards, in order to guide further training and confirm readiness.
Context Anchor
Used in ground lessons, flight lessons, simulator sessions, stage checks, and post-flight debriefs.
Derivation
From the Latin assidere, meaning 'to sit beside.' The original sense was a judge or advisor sitting beside someone to weigh a matter. That image fits the instructor sitting beside the learner, weighing their performance and helping them improve.