The adjective definable describes something that is capable of being explained or described. Your children will do better with a few definable rules. "Don't hit anyone" is much clearer to a three-year-old than the vague "don't do anything you wouldn't want someone to do to you."
Definable is based on the word define, which is from the Latin word definire, meaning to limit or explain. You can take a definable risk if you understand the boundaries and consequences of the risks involved. Knowing the limits can help you make an informed decision about whether the risk is worth it. Exceeding the speed limit is definable, because driving rules are spelled out in manuals and you will get a ticket if you are caught.
