上下

the nobility and the commoners

volumes one and two of a two-volume book or other document

(clothing) a suit, a set of clothing consisting of garments for the upper and lower body

rising and falling, ascent and descent

the high and the low, the upper and the lower

the city and the country (the city is considered “up”)

north and south (north is considered “up”)

roundtrip travel on a river, going both upstream and downstream

high rank and low rank

the lord and the ministers

the old and the young

an exchange of words, a discussion, question and answer