The word "yechy" is generally used to describe something unappealing, unpleasant, or distasteful. It is a slang term and might not be suitable for formal communication. If you are looking for alternative words to replace "yechy," you can go for adjectives such as disgusting, revolting, nauseating, vile, repulsive, gross, and loathsome. Moreover, you can also use terms like unpalatable, detestable, abhorrent, unappetizing, and unsavory to convey the same meaning. If you want to use more formal vocabulary, you can try using phrases like repugnant, offensive, off-putting, or objectionable instead. Keep in mind to choose an appropriate word depending on the context.