ツイ, お.う, おい
chase, drive away, follow, pursue, meanwhile
JLPT3 G3 S9 F411
?is a tall pile of (heavy) objects exerting downward pressure. 追 adds 辵 movement → pressure an enemy army by pursuing it → *pursue*/*follow*; *drive off/out*; *expel*; *catch up with* → *add*.
[Full Kanji Etymology List]