What is a synonym for horizontal?

Here are some synonyms for "horizontal," depending on the specific context:

General:

* Level

* Flat

* Parallel to the horizon

* Across

* Lateral

* Transverse

More specific:

* Recumbent (lying down)

* Prone (lying face down)

* Supine (lying face up)

* Reclining (leaning back)

* Parallel (specifically when referring to lines or surfaces)

The best synonym will depend on the specific meaning you want to convey.