Where did the term sheila come from?

The term "sheila" is commonly believed to have originated from Australian English, likely derived from the Irish name "Síle," which is the Irish equivalent of "Cecilia." It became a popular slang term in Australia during the 20th century, often used to refer to a woman or girl. The term reflects the influence of Irish immigrants on Australian culture and language. Over time, "sheila" has been embraced in various contexts, sometimes affectionately, but can also carry connotations depending on usage.