Carninormative is a label referring to the idea that our society assumes that eating meat is acceptable, desirable, and most importantly, unremarkable. This can be a problem for vegetarians and vegans, who have to learn a complicated vocabulary of technical terms to determine if food contains meat byproducts, have to double-check that 'vegetarian' options are really vegetarian, and have to explain that 'meat' does include chicken. And fish. And lard. And rennet. And etc.
Our culture is not just carninormative, but overwhelmingly so. While foods are often clearly labeled as kosher, organic, and fair trade, and nutrition information regularly includes labeling of saturated fat, trans fat, polyunsaturated fat, and monounsaturated fat, it is not only common for animal products to go unlabeled, but it is also common for them to appear in foods marketed as vegetarian and vegan. Avoiding eating foods that have had animals intentionally killed in their production is perhaps the most research-intensive dietary restriction, requiring everything from a knowledge of sugar sourcing in your country to an extensive vocabulary of ultrapolysyllabic words.
It is also common for a carninormative culture to consider the use of words like carninormative as ridiculously smug and snobbish. They would much rather be referred to simply as carnivores, perhaps on the theory that eating meat is a state of nature rather than an ideological choice. Which is obviously a very carninormative way to think.