know (someone or something) through and through

know (someone or something) through and through

To have a thorough and complete knowledge of someone or something. I know Elizabeth through and through, so I really doubt that she's hiding something. A: "You can recite that poem from memory?" B: "Sure, I know it through and through."
See also: and, know, through
Farlex Dictionary of Idioms.

know something through and through

to know something very well. I want you to know this project through and through before the staff meeting. I know my part in the play through and through.
See also: and, know, through
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • (someone or something) promises well
  • a/the feel of (something)
  • a straw will show which way the wind blows
  • (I) wouldn't (do something) if I were you
  • (have) got something going (with someone)
  • accompanied by
  • accompanied by (someone or something)
  • accompany
  • a crack at (someone or something)
  • all right