Addlings refer to the offspring of birds or young birds that are unable to fly. There are several other terms used to describe this state, including chick, fledgling, nestling, and hatchling. A chick is a young bird that has hatched from the egg but has not yet grown feathers. Fledglings are birds that have grown their initial feathers and are able to move around. Nestlings are birds that are still in the nest, while hatchlings are newly hatched birds. All these synonyms allow for a more specific way to describe birds and their developmental stages. So, whether it's a chick, fledgling, nestling, or hatchling, they all have their unique qualities and characteristics that make them interesting to observe and learn about.