façon de parler (n.)
A turn of phrase or rhetorical formula, especially one that ought not to be taken literally, but rather as employed for convenience of expression only. Wiktionary
A way or manner of speaking; a mere phrase or formula.
S. H. Hodgson Let. 8 Apr. in R. B. Perry Thought & Char. W. James (1935) I. 642 What is ‘the mind’?.. I suspect it is a mere façon de parler..which has a basis neither in psychological construction nor in philosophical analysis.
1907 W. De Morgan Alice-for-Short xlii. 439 Which was palpably a lie, taken literally; but was a façon-de-parler that passed muster, taken leniently. OED
Let us distinguish in mental phenomena a virtual part implemented by neurophysiological processes and a fictitious part not implemented at all, that is an illusion (or an idealization, or a mere façon de parler) whose introduction in our language sometimes may be quite useful but that strictly speaking does not exist. Oscar Vilarroya et al.; Social Brain Matters (2007)
There are no discrete unities identical to themselves and different from others. Distinguishing between natural kinds is merely façon de parler, referring only to a certain way of perceiving reality. Robert Spaemann; Essays in Anthropology (2010)
On the other hand, I do not know of any significant study of postmodernism that sees it object as a "reality" that is out there, to be discovered and mapped. What may appear as a result of the mimetic illusion is almost always a mere façon de parler, which is based on certain mimetic metaphors (the mind as a mirror, the mirror of nature, etc.) built into our language. M. Calinescu in M. Calinescu and D. Fokkema (eds.); Exploring Postmodernism (1987)
When he says " paranoid streak", he does not really mean the term" paranoid" to be taken seriously—it is just a facon de parler. Stephen Toulmin; The Return to Cosmology (1985)