Which adjective would best describe someone who is never drunk?

The adjective that best describes someone who is never drunk is "temperatus." This Latin word translates to "moderate" or "restrained," suggesting self-control, particularly in relation to the consumption of alcohol. Someone who is never drunk would exhibit a temperament that avoids excess, aligning perfectly with the notion of moderation associated with being "temperatus."

The other adjectives do not convey the same meaning. "Ebrius" means "drunk" or "intoxicated," which is the opposite of what we are looking for. "Potent," meaning "powerful" or "strong," does not specifically relate to one's state of sobriety or drunkenness. "Innocente" translates to "innocent," which may imply a lack of experience or wrongdoing but does not directly address the matter of sobriety or the absence of drunkenness. Therefore, "temperatus" is the most fitting adjective for someone who is consistently sober.