What is an antonym for the prefix sub?

There isn't a single perfect antonym for the prefix "sub" because it depends on the context. "Sub" can have several meanings, leading to different antonyms.

Here are some possibilities:

Meaning: "Below" or "under"

Antonym: Super, Hyper, Over, Above

Example:

* Submarine (below the surface) - Supermarine (above the surface)

* Subsoil (below the top layer) - Topsoil (the top layer)

Meaning: "Less than" or "lower"

Antonym: Super, Hyper, Over, Greater, Higher, Upper

Example:

* Substandard (less than the standard) - Superior (above the standard)

* Subcommittee (a smaller committee) - Main committee (the larger, primary committee)

Meaning: "Secondary" or "assistant"

Antonym: Chief, Main, Primary, Principal

Example:

* Subcontractor (secondary contractor) - Main Contractor (primary contractor)

* Subordinate (an assistant) - Superior (the main leader)

Ultimately, the best antonym for "sub" will depend on the specific word it's attached to and the intended meaning.