The phrase "a popular expression" is correct and usable in written English.
It can be used when referring to a phrase or saying that is widely recognized and commonly used by people.
Example: "The phrase 'time flies' is a popular expression that reflects how quickly time seems to pass."
Alternatives: "a well-known saying" or "a common phrase".
"A popular expression signalling a collapse of will".
("We make the paint" is a popular expression of humility).
— for "kuuki yomenai" — a popular expression that literally means "can't read the air" or "clueless".
These books have sold in their hundreds of thousands, reflecting a popular expression of angry US conservatism.
"Part of my reluctance is that the name of your company rhymes with a popular expression," the visitor confided.
The cymanfa ganu ("singing festival") has been a popular expression of religious Nonconformism since the mid-19th century.
The methylotrophic yeast Pichia pastoris has become a highly popular expression host system for the recombinant production of a wide variety of proteins, such as antibody fragments.
There is an equally plausibly historical narrative of Egyptian politics over the last century, which would emphasize the role of an elected legislature in politics both as a representative of popular expression and as the ultimate arbiter of government decisions.
Addressing climate change is a product of popular expression, low-carbon options and global political leadership, which generally sees the issue as having profound environmental and economic implications.
Ratzinger's election as pope on the second day of the conclave was something of a surprise because of his status as a leading candidate; front-runners are almost never chosen, a fact reflected in the popular expression, "He who enters as a pope leaves as a cardinal".
At the moment they are being featured more prominently than they have been in nearly two decades, in "Testimonios: 100 Years of Popular Expression," a kaleidoscopic display of more than 300 works drawn almost entirely from El Barrio's collection.
