Gerris refers to a water strider, a type of insect that can walk on the surface of water. There are a few synonyms that one could use to describe a gerris in a scientific manner. One of the synonyms could be "Heteroptera," which is the scientific name for the order of insects that a gerris belongs to. Additionally, one could describe a gerris as a "Halobates," which is the genus name for marine water striders. Lastly, a general term that could be used to describe a gerris could be "aquatic bug," which encompasses all types of bugs that live in aquatic environments.