Onomatopoeic words, or imitative words, are those that were created to duplicate certain sounds. Animal noises such as “bark,” “neigh,” and “hiss” fit the bill, but so do more human activities such as “hum,” “shush,” and “clap.” Those onomatopoeias are pretty straightforward, but “flibbertigibbet” was created for an excessively talkative, flighty sort of person. Just imagine a chatty character, cheeping away so quickly that you can’t quite make out what they are saying — it might sound like “flibbertigibbet.”