A patsy is someone who is easy to trick — especially someone other people set up so that this person takes the blame. If a group does something wrong and then points at the quiet one, that person is the patsy: the one left holding the bag while the others walk away.

It is informal American slang. You hear it in crime stories, films, and political news (“they needed a patsy”). It is not a kind word, and it is not for a school essay unless you are quoting. It is a bit old-fashioned in everyday speech, but it has not died.

Where the name came from, nobody agrees, so this is reaching if we pretend we know. The word is attested in the United States by the 1870s, around a peak of Irish migration; some scholars tie Patsy to Pat and Paddy, the cruel comic picture of an Irish newcomer “just off the boat.” Others mention Italian pazzo (“madman”) or southern Italian paccio (“fool”). Another guess points at a stage character, Patsy Bolivar, who got blamed whenever anything went wrong. Treat all of these as “people have guessed,” not as a settled family tree.