Passableness refers to the quality or state of being capable of being traversed or crossed. There are several synonyms for this term, such as accessibility, navigability, permeability, and openability. Accessibility refers to the ease with which a place or object can be approached. Navigability, on the other hand, pertains to the ease with which it is possible to travel or navigate through a body of water. Permeability refers to the degree to which a substance or material can allow liquids or gases to pass through it. Lastly, openability denotes the ability of an object to be opened or unsealed. These synonyms can be used interchangeably depending on the context of the sentence.