An ocean trench is an underwater depression with steep sides that forms a boundary between tectonic plates. There are several synonyms for the word 'ocean trench' which are used interchangeably in different contexts. The most common synonyms are 'abyssal plain', 'deep-sea trench', 'oceanic trench', 'deep-sea canyon' and 'marine trench'. Each of these synonyms offers unique insights into the nature of the geological features that form ocean trenches. These terms are used often in the field of oceanography and marine biology to describe the diverse ecosystems that are found in deep-sea environments. Whether exploring the deepest parts of the ocean or studying the fascinating geologic features that form ocean trenches, the synonyms for 'ocean trench' provide a wealth of vocabulary to help us better understand this fascinating underwater world.