The word "neddy" is a slang term for a horse, but there are many other synonyms that can be used instead. Some of the most common ones include equine, steed, nag, mount, charger, mare, stallion, colt, and filly. Other synonyms that may be less well-known include courser, palfrey, hack, cob, gelding, and hunter. Many of these words have different connotations and can be used to describe different types of horses or different situations. For instance, "courser" implies a fast and agile horse, while "palfrey" is a term used for a riding horse that is gentle and easy to ride.