More general terms:
* Littoral - This is a common synonym for "intertidal," but it can also refer to the entire area between the high and low water marks, including the subtidal zone.
* Shoreline - This is a broader term that encompasses the entire area where land meets water.
* Coastal - This refers to the area near the coast, which includes the intertidal zone but also other areas.
More specific terms:
* Tidal - This emphasizes the influence of tides on the area.
* Eulittoral - This is a more technical term that specifically refers to the area between the high and low tide marks.
* Nearshore - This term can be used to describe the area near the shore, but it might not be specific enough for the intertidal zone.
Other options:
* Tidal zone - This is a more descriptive phrase, but it isn't strictly a synonym.
* Between the tides - This is a straightforward and accurate description of the intertidal zone.
The best synonym for "intertidal" will depend on the specific context and what aspect of the term you want to emphasize.