Verisimilitude
Etymology
From Latin "verisimilitudo," built from verus, "true," and similis, "like" — literally "likeness to the truth." It entered English in the seventeenth century as a term for the appearance, rather than the fact, of reality. The distinction matters: a story can have great verisimilitude while being entirely fictional.
noun · /ver-ih-sih-MIL-ih-tood/
The quality of seeming true or real, even in a work that is invented.
What it names
The convincing texture of small accurate details that makes a novel or film feel lived-in, giving you a word for believability as distinct from literal truth.
Example
The screenwriter spent a week shadowing paramedics purely for verisimilitude, and the ambulance scenes are all the more gripping for it.
Related idea
Verisimilitude is the feeling of truth; realism is a broader artistic program committed to depicting ordinary life plainly.