What is another word for all sweetness and light?
Pronunciation: [ˈɔːl swˈiːtnəs and lˈa͡ɪt] (IPA) 
"All sweetness and light" is an idiom that means overly pleasant or excessively agreeable behavior. Some synonyms for this phrase are insincere, phony, fake, overly-friendly, and coquettish. Another phrase that conveys a similar message is "too good to be true," which implies that something or someone is perhaps hiding their true motives or intentions. Moreover, "smarmy" and "buttery" are additional synonyms that suggest a false sense of affability or sugary behavior. Therefore, when trying to describe someone or something as over the top sweet, there are a variety of words to choose from, all which can be used to convey a sense of artificial or exaggerated friendliness.
