The phrase "debut novelist" refers to a writer who is publishing their first-ever book. It describes an author who is new to the literary world and has never written or published a book before. Full definition
How many 70 - year - olds can also claim the title of best - selling debut novelist? (bookpage.com)
For debut novelist Edward Kelsey Moore — already an accomplished professional cellist and college professor — writing was that something new. (bookpage.com)