上界

上界	shàng jiè	upper bound
上	shǎng	used in 上声
上	shàng	(bound form) up; upper; above; previous / first (of multiple parts) / to climb; to get onto; to go up / to attend (class or university) / (directional complement) up / (noun suffix) on; above
界	jiè	(bound form) boundary; border / (bound form) realm