What term describes a young pigeon before it's fully grown?

The term that describes a young pigeon before it is fully grown is "squab." This word specifically refers to a young pigeon that is typically still in the nest and is dependent on its parents for food and care. Squabs are usually characterized by their lack of full feathering and are generally at a stage where they are not yet able to fly.

In contrast, “fledgling” refers to a young bird that has acquired enough feathers to leave the nest and begin flying, which is a more mature stage than a squab. "Cuddler" does not pertain to any specific stage of a bird's growth and is not a recognized term in ornithology. "Nester" describes a pigeon that is in the process of creating or occupying a nest, rather than referring to its developmental stage. Thus, "squab" accurately conveys the specific early growth stage of a young pigeon.