Final answer:
Defiantly describes an attitude, not the physical action of stretching one's neck. Words like 'craning' or 'extending' are more appropriate to describe the action without any connotation of defiance.
Step-by-step explanation:
The action of stretching one's neck doesn't have a specific term related to defiance. Defiantly is not a word that describes the physical action of stretching the neck but rather describes an attitude or manner in which an action is done. For instance, if someone 'said something defiantly' it refers to the tone used, indicating resistance or challenge.
Looking at the various contexts provided, such as a person stretching a rubber band, a character experiencing a pang in the neck, or a bold, defiant tone in a conversation, we see that defiance is about an assertive stance or emotion rather than a specific physical movement.
Therefore, while there is no exact word for the action of stretching one's neck, 'defiantly' does not fit as that descriptor. It would be more appropriate to describe the physical action without the connotation of defiance, such as 'craning' or 'extending' one's neck.