Idiom Definition:
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"to know what's what"
to understand a situation even though the facts might not be apparent or the facts might be unpleasant
Synonyms:
apprehend, aware, catch, cognizant, comprehend, conversant, discern, fathom, get, grasp, infer, informed, intuit, ken, know, learn, learned, master, perceive, recognize, register, savvy, see, understand
This person
literally knows what's what. - - - - ->