甜 is not securely known from oracle-bone writing; its early recorded forms belong to a later stage of the script. They combine 舌, “tongue”, with 甘, “sweet” or “pleasant-tasting”. Older dictionaries also record the reversed form 甛. This hand-drawn ancient-form sketch keeps those two taste-related parts distinct rather than inventing an oracle-bone picture.
A piece of culture
Sweetness at the table 甜 is the everyday word for a sweet taste. 甜品 means “dessert” or “sweet dish”: tiánpǐn in Mandarin and tim4 ban2 in Cantonese. In Cantonese food culture, 甜品 can include warm sweet soups as well as chilled puddings, tofu desserts and fruit-based treats — a whole course defined by this one taste.