The phrase "a primary subject" is correct and usable in written English.
It can be used when discussing the main topic or focus of a discussion, study, or piece of writing.
Example: "In this research paper, the primary subject is the impact of climate change on marine biodiversity."
Alternatives: "a main topic" or "a central theme".
"Women are not a primary subject of discussion," Mr. Halman said.
A book should have an intellectual shape and a heft that comes with dealing with a primary subject.
The work has been smoothly Americanized, down to character and brand names; a primary subject is consumerism.
Because the core of the Rangers is young, a primary subject Sunday was how satisfied they should be with advancing to the conference finals.
It is incumbent upon the international community to ensure that immediately ending the human rights abuses of his government is a primary subject of the talks, and that it remains as a precondition to any broader settlement.
After the turn of the century, the city itself became a primary subject of painting, though early American modernism might be viewed as an effort to transplant nature from country to town.
Sex wasn't just a favorite recreational activity; it was a primary topic of conversation and subject of study.
It's not easy, as an artist, to make your primary subject a certain sound.
More than 40 black-and-white and five color photographs from 1972-74, manevervexhibitedted before, document Ms. Goldin's early years as a photographer in Boston, when her primary subject was a clique of drag queens.
His primary subject, an often-strident Zakaria Soubra, belonged to a British group that espouses the creation of a single Islamic state worldwide.
It cannot be said that he eventually chose a dog as his primary subject in order to slip under the wire of censorship.
