0 Old HSK word(s):
知己知彼* *

Definitions from Unihan Copyright © 1991-2015 Unicode® Inc. All rights reserved.

知 know, perceive, comprehend
己 self, oneself / personal, private / 6th heavenly stem
知 know, perceive, comprehend
彼 that, there, those
Hsk Characters:
HSK -Characters and beyond:
GbBig5EngRadMegaTripleMultilingual