The antonym of the word orthodox is unconventional.
- Orthodox means conforming to the traditional or generally accepted way of doing things.
- Unconventional means not conforming to the traditional or generally accepted way of doing things.
The other words do not have opposite meanings to orthodox.
- Usual means happening or done regularly or typically.
- Plentiful means existing or available in large quantities.
- Sound means based on good judgment or common sense; sensible.
| 
