Definition
"Outmost" is an older, less common synonym for "outermost." It means the farthest away from the center or the inside. It's essentially the same as outermost, indicating the most external or peripheral point. Think of it as being at the very edge or boundary. Though you don't hear it often, it emphasizes the idea of being the furthest extent. You'd use "outermost" in most situations, but knowing "outmost" expands your vocabulary.