If someone is estranged from another person, they no longer have a friendly relationship with that person.
The word estranged has a sad feeling. It means that two people who used to be close are not close anymore.
Examples:
They used to be friends, but now they are estranged.
The estranged sisters haven't spoken in years.
The estranged brothers live in different cities now.
The estranged couple sat on opposite sides of the room at the party.
The estranged best friends never see each other anymore.
The estranged neighbors used to have barbecues together, but now they don't even say hello.