出

出 (chū) means 'to go out / come out / exit' — the directional opposite of 进 (jìn, 'enter'). On its own it can be a full verb (太阳出来了 'the sun has come out'), but it most commonly appears as a directional complement attached to other verbs to mark outward motion: 走出 ('walk out'), 跑出 ('run out'), 拿出 ('take out'), 说出 ('speak out / utter'). Adding 来 or 去 specifies direction relative to the speaker: 出来 ('come out — toward me') vs 出去 ('go out — away from me'). 出 also appears in countless high-frequency compounds: 出门 ('go out the door / leave home'), 出发 ('set out / depart'), 出生 ('be born'), 出租车 ('taxi,' literally 'rent-out car'), 出口 ('exit; export'), 出现 ('appear'). Beyond physical motion, 出 carries the abstract sense of 'producing, emerging, or revealing' — 出问题 ('a problem comes up'), 看出 ('see / figure out'). It is one of the most productive single characters in Chinese.

Memory hook: The character 出 looks like one mountain (山) stacked on top of another — climb up and OUT, away from where you started.