What is the meaning of correspond?

verb

• Be compatible, similar or consistent; coincide in their characteristics.
  • usage: "The two stories don't agree in many details"; "The handwriting checks with the signature on the check"; "The suspect's fingerprints don't match those on the gun"
  • synonyms: match, fit, check, jibe, gibe, tally, agree
• Be equivalent or parallel, in mathematics.
  • synonyms: equate
• Exchange messages.
  • usage: "My Russian pen pal and I have been corresponding for several years"
• Take the place of or be parallel or equivalent to.
  • usage: "Because of the sound changes in the course of history, an 'h' in Greek stands for an 's' in Latin"
  • synonyms: represent, stand for