Hello, you have come here looking for the meaning of the word flu. In DICTIOUS you will not only get to know all the dictionary meanings for the word flu, but we will also tell you about its etymology, its characteristics and you will know how to say flu in singular and plural. Everything you need to know about the word flu you have here. The definition of the word flu will help you to be more precise and correct when speaking or writing your texts. Knowing the definition offlu, as well as those of other words, enriches your vocabulary and provides you with more and better linguistic resources.