the word "yum-yum" is a playful, reduplicative formation based on the earlier interjection "yum," which first appeared in english in the late 19th century. "yum" itself is an onomatopoeic creation, meant to imitate the sound of someone savoring delicious food, such as a lip-smack or a hum of satisfaction. the reduplicated form "yum-yum" serves to intensify this expressive quality, emphasizing great pleasure and delight. as a lexicalized example of sound symbolism, it demonstrates how language can create words that directly mimic sensory experiences, in this case, the enjoyment of eating.

this is a reduplicative compound, formed by repeating the expressive syllable "yum". it is an onomatopoeic formation, imitating the sound of pleasurable eating or lip-smacking.