adj. colloq. delicious, delectable; also as int.
According to the Oxford English Dictionary, the first recorded use of "yummy" was in 1899: "R. Kipling Rudyard Kipling Stalky & Co. Stalky and co 239 Pretty lips..Seem to say—Come away. Kissy! come, come!.. Yummy-yum-yum!"
I don't know why, but yummy creeps me out. It's like some people and their problem with the word "moist". It just sounds gross and nothing like a word I would apply to food, whether enjoyable or no. I think this quote from The Vocabula Review's list of "The Worst Words" pretty much sums up my feelings about yummy, irrational or no:
Do I need to explain this? The sound makes my skin crawl, not only for the appalling lack of vocabulary it reflects in its user, but in the visual imagery it evokes in envisioning either the item described or visage of person from whom this hideous word emanated.
In my opinion it is slightly overused and what for? There are so many other wonderful, more descriptive, more picturesque words when using to describe an enjoyable dish - whether the dish is food or human, ha! Unfortunately it has been and continues to be used by people I like, so I can't very well get away from this... word. And since disliking a word is a silly thing with little to no rational basis, I'm certainly not going to tell my loved ones to stop using it.