The phrase "boyfriend jacket" refers to a style of jacket that is oversized and loose-fitting, mimicking the look of a jacket borrowed from a boyfriend. Full definition
The grey boyfriend jacket outfit with the hat is my favourite combination. (nofearoffashion.com)
At the conference they were offering boyfriend jackets with embroidery to attendees at a very affordable price, so I said why not? (stylishparadox.com)
An ivory boyfriend jacket and black distressed jeans... classics, part II. (wendyslookbook.com)