What does "come across" mean?

Also, come upon; run across. Meet or find by chance, as in I came across your old letters today, or He came upon her looking in the store window. or If I run across it, I'll call you. The first term dates from the 1800s. The first variant was used by Oliver Goldsmith in She Stoops to Conquer (1773): “You are to go sideways till you come upon Crack-Skull Common.” The second variant was used by Mark Twain in Tramp Abroad (1880): “If I don't run across you in Italy, you hunt me up in London.”

Also, come across with. Pay or give what is expected or demanded, as in He finally came across with some food, or The landlord wants the rent, so come across. [Colloquial; late 1800s]

Make a particular impression, as in He comes across as a very sincere person or Her meaning doesn't really come across; she'll have to revise the speech. [Colloquial; first half of 1900s] Also see get across; put across.