General terms:
* Green: This is a common term for an untrained or inexperienced horse. It refers to the horse's lack of knowledge and skills.
* Unschooled: This term emphasizes that the horse has not been formally trained in any specific discipline.
* Unbroken: This refers to a horse that has not been trained to accept a rider.
* Rough: This term indicates a horse that is still wild or unmanageable, with little or no training.
Terms related to specific disciplines:
* Young horse: This is a general term for a horse that is still developing, regardless of its training level.
* Starter horse: This refers to a horse that is just beginning its training in a particular discipline, such as show jumping or dressage.
* Beginner horse: This refers to a horse that is suitable for a beginner rider, meaning it is calm, well-trained, and forgiving.
Other terms:
* Colt: This refers to a young male horse that is not yet castrated.
* Filly: This refers to a young female horse.
Ultimately, the best term to use depends on the specific context and what you want to emphasize.