Barkless is a word that could mean different things depending on the context in which it is used, such as lacking the sound of a dog's bark or lacking rough texture on the surface. In terms of the latter meaning, there are many synonyms that could be used instead, such as smooth, sleek, glossy, polished, or even velvety. These words could be applied to describe anything from fabric and surfaces to animals with smooth, hairless skin. But when it comes to describing dogs, the term non-barking or quiet could be used as synonyms for the word barkless, indicating that the dog is not prone to making loud, barking noises.