the.com/force field

means An invisible barrier of energy that blocks or repels physical matter, keeping things in or out without any solid material there at all.

from Pure 20th-century coinage, born from physics before science fiction ran off with it. 'Field' comes from the mathematical/physical sense established in the 1800s — a region of space where a force (magnetic, gravitational, electric) has measurable effect at every point, borrowed from the everyday 'field' as an open expanse. Michael Faraday and others developed the concept of fields to explain how forces act at a distance without visible contact. 'Force field' as a term for an invisible protective barrier — the kind you can't touch but definitely can't walk through — is a pulp science-fiction flourish built on that real physics vocabulary, picked up and popularized through decades of comics, film, and TV until it became the default word for any shimmering wall of nothing.