What does "epiphenomenal" mean?

Being of secondary consequence to a causal chain of processes, but playing no causal role in the process of interest.

How do you pronounce "epiphenomenal"?

Pronounced //ˌɛpɪfɪˈnɒmɪnəl//.

//ˌɛpɪfɪˈnɒmɪnəl// adj

adj ·Rare ·Advanced level

Adjective

1
Being of secondary consequence to a causal chain of processes, but playing no causal role in the process of interest.
"An organism's consciousness is epiphenomenal to its behavior, and its behavior is determined by unconscious calculations."
2
Of or pertaining to a mental process that occurs only as an incidental effect of electrical or chemical activity in the brain or nervous system.
"If qualia are epiphenomenal in the standard philosophical sense, their occurrence can't explain the way things happen (in the material world) since, by definition, things would happen exactly the same without them."

"An organism's consciousness is epiphenomenal to its behavior, and its behavior is determined by unconscious calculations."

From epi- + phenomenal.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.