Desertless, meaning "without desert," is a rare term and therefore there aren't many synonyms that convey the same exact meaning. However, there are several synonyms that could be used in its place depending on the context of the sentence. One option is to use the phrase "free of desert." Alternatively, one could say "uninhabitable" if referring to an area without vegetation or resources. Another option would be to say "lush" or "fertile" if talking about an area with abundant vegetation. "Moist" or "humid" could be used if referring to a place with a high level of moisture or rainfall. Finally, "habitable" could be used to describe any area suitable for human settlement regardless of whether it has a desert or not.