Something -- usually food -- that is so absolutely delectable and delicious that you must define it by the sound you make while eating it - "NOM NOM NOM".
This usually defines things found on Thanksgiving, like Mashed 'Taters and gravy, Mac and Cheese, and Ice Cream.
Occasionally it may refer to a person, but it's not recommended to do so, as it can be very insulting.
Oh my God, that turkey last night was absolutely nomlicious! I couldn't stop eating!
Janice, this fresh apple pie is absolutely nomlicious, you put just the right amount of cinnamon in it!
Daa-a-amn, that girl's booty is nomlicious, oh I could hit that! Mm!