Nabisco is a big US food company, known especially for packaged cookies, crackers, and breakfast foods. If you have eaten an Oreo or a Ritz cracker, you have met the kind of supermarket snack people connect with this name. It is a company name, so it takes a capital N and does not have a plural: you buy Nabisco cookies; you do not eat “a nabisco.” In ordinary American talk the word lives on boxes and in brand talk more than in everyday chat. Though actually, the company has been bought and folded into larger food groups over the years, so the old brand name on a packet and the name of today's owner are not always the same thing — but Nabisco is still widely recognised.