Non-buoyant is a term that describes an object that sinks or cannot float. There are several synonyms for this word that can be used interchangeably depending on the context of the sentence. Some possible synonyms for non-buoyant include heavy, dense, sunken, immobile, inactive, sluggish, and unresponsive. These terms can be used to describe a wide variety of objects, ranging from rocks and metals to emotions and attitudes. When considering the appropriate synonym, it is important to identify the specific characteristics of the object in question and choose a word that accurately conveys its properties.