"Faddily" is a relatively uncommon word, meaning something that is characterized by trends or passing fads. There are a few different synonyms that can be used to convey a similar meaning. One option is "trendy," which refers to something that is currently fashionable or "in." Another option is "fashionable," which similarly suggests that something is being embraced by many people at a particular moment. "Faddy" and "flaky" are other possibilities, with the former referring to something that is subject to passing whims or fancies, and the latter suggesting that something is unstable or unpredictable. Overall, there are a range of words that can be used to convey the sense of something being faddily.