The phrase "narrow definition" refers to a specific or limited explanation or understanding of something, rather than a broad or comprehensive interpretation. Full definition
As a society, we have a very narrow definition of what happiness is: fame, wealth, power, and prestige. (mindbodygreen.com)
They began with a very narrow definition of climate change as only those changes caused by humans. (drtimball.com)
But the panel of airline and advocacy experts was unable to reach a consensus on narrowing the definition of what qualifies as a comfort animal. (ktvb.com)