可

Possibility or permission; worthiness, propriety, or acceptability; affirmation (yes, indeed).

• Modal Auxiliary: Marks logical/physical possibility ("it is possible that") or social/moral permission ("one may").
• Evaluative Modifier: Used to transform a verb into an evaluative adjective (e.g., "-able").
• Predicate: When standing alone, denotes that something is acceptable, sufficient, or fits requirements.
• Particle of Affirmation: In dialogue or argumentative prose, marks agreement or confirmation.

Contrast with 能: while both may be translated as "can," 能 generally denotes inherent capacity or physical ability, whereas 可 denotes external possibility, permission, or appropriateness.

Tang-period reading: *kɑ̌ (Fanqie: 枯我).

In short phrases, there is frequent overlap between the modal use ("can do X") and the evaluative use ("is worthy of doing X"). This distinction shifts the tone from a statement of capability to a value judgment.