From The Art and Popular Culture Encyclopedia
In literature and theatre, the term denotes the extent to which a work of fiction exhibits realism or authenticity, or otherwise conforms to our sense of reality. A work with a high degree of verisimilitude means that the work is very realistic and believable; works of this nature are often said to be "true to life".
In theatre, verisimilitude refers to a neoclassic idea of reality (realism), morality (there is a god), and universality. Universality means that common of all people, there is a truth. Something that is true of one person is true of all.
Verisimilitude in Philosophy of Science
The term Verisimilitude has also served the purpose, in the philosophy of science, of trying to articulate how a false theory could be closer to the truth than another false theory. This usage was mostly popularized by Sir Karl Popper. His logical definition of Verisimilitude was independently shown inadequate by Pavel Tichý and David Miller, and the search for such a logical definition is still underway.