This idiom means to release pent-up emotions, stress, or energy through vigorous activity, venting, or relaxation. It suggests relieving pressure in a healthy or expressive way, often used in contexts of frustration, anger, or overwork, with a sense of catharsis.

The phrase comes from 19th-century steam engines, where excess steam was released to prevent explosions.

It appeared in American English by the 1830s, with an 1837 *Knickerbocker Magazine* article using ‘blow off steam’ to describe emotional release.

By the late 19th century, it was common in literature, including Mark Twain’s works,
reflecting industrial-era imagery. Its use grew in the 20th century, especially in psychology and workplace contexts.