Definition & Meaning of "geezer"in English

What is the origin of the term "geezer" and how is it used?

"Geezer" is British slang that emerged in the early 20th century, originally meaning simply an old man. The word may come from a dialectal shortening of "guiser," referring to someone in disguise or costume, which later shifted to mean a quirky or distinctive character. Over time, it came to describe not just any elderly man, but often one who is eccentric, rough around the edges, or colorful in personality. It is widely used in informal speech, especially in the U.K., and is generally neutral, though context can make it affectionate, teasing, or mildly derogatory.