Vanner is a relatively uncommon word with few established synonyms. It is generally used to describe a type of horse that is bred specifically for its ability to perform a smooth trotting gait, making it ideal for carriage driving. However, some may use the word vanner to refer to any type of carriage horse. Some potential synonyms for vanner include trotting horse, carriage horse, carriage driving horse, or simply horse for carriage use. However, it should be noted that none of these terms specifically denote the unique traits and breeding of a vanner horse and may not convey the same meaning or connotation.