逆

Core sense: Movement against a flow or current.

• Physical/Spatial: Moving against the wind or water; meeting someone coming from the opposite direction (often a neutral description of travel).
• Social and Political: Disobedience toward social hierarchy, filial piety, or imperial command; acting as a rebel or traitor.
• Philosophical/Cosmic: Acting in contradiction to the natural order (Dao) or Heaven’s Will.
• Sensory/Medical: A sense of stiffness or "rebellious" flow (e.g., qi moving in the wrong direction), more common in later technical texts.

• Verb: To oppose, resist, go against, or meet.
• Adjective/Modifier: Contrary, opposite, perverse.
• Noun: A rebel or traitor.

Contrast with 反 (fǎn): While both can be translated as "rebel," 逆 suggests friction and persistent resistance against an established current or order, whereas 反 suggests reversal, inversion, or a total flipping of positions.

The specific meaning is generally determined by the object of the opposition:

• Natural elements (wind, water) → Directional/Physical.
• Persons/Authorities → Disobedience/Rebellion.
• Abstract principles/Dao → Metaphysical contrariness.
• No explicit object → Likely refers to a general state of perversity or "going against the grain."