unwelcome

"You are not welcome here." or "Go away."

Unwelcome

When guests arrive at your door, you might say "Welcome!" It means you are happy to see them, and hope they are about to have a good time with you. When they leave, you might say "Farewell!" It means you were happy to see them, and hope they are about to have a good time on their trip home. "Welcome" and "Farewell" are not opposites, but they are a pair like "Hello" and "Goodbye." "Welcome/Farewell" are more formal and stronger than "Hello/Goodbye." You say "welcome" when people are coming to visit you in your house, and you are offering them "hospitality." They are coming to a party, or to dinner, or possibly saying overnight with you. Both might be the start of a little speech. "Welcome! Come on in! Sit down, make yourself at home, it's great to see you!" "Farewell! Have a good trip! It's been wonderful having you, don't be a stranger, come back soon!" "Welcome" can be an adjective. In this usage, the opposite is "unwelcome." "Whenever I visited, my aunt always made me feel welcome. But my uncle was cold and distant. He never said anything, but somehow he made me feel unwelcome."

If you mean when someone departs, the opposite term is "farewell". For example, a "welcome ceremony" and a "farewell ceremony".