Chameleon is puffing our its throat (gular)
The throat area is puffed out showing colors and patterns.
Meaning: A puffed out throat, or gular, is an attempt top make the chameleon look bigger than they are and to scare off the intruder. Chameleons will exhibit this behavior when they feel threatened and are scared
When a chameleon feels threatened it will both try and make itself look as big as possible and warn that a bite is imminent. If it is a threat display the gaping will be accompanied by an inflating of the gular (throat,) a flattening of the body, bright colors, and the front hand (or hands) being drawn up into the body.
This is not a reason to worry other than a sign that you should remove the stressor. If it is you invading their cage space to give them food then they will get over it when you retreat. If they are reacting to a pet bird, for example, then change the cage location so they do not have whatever they feel threatened by around them. This can often happen in situations where chameleons are kept together. in the same cage. the solution, of course, is to separate the chameleons into their own cages and put up a visual barrier if there still is an issue.
This Panther Chameleon is giving a half hearted warning of being annoyed. She does not like human intrusion in her cage, but has been raised from the egg being served by this human so she does not seem to have much vigor behind her warning.
This Meller’s Chameleon is in a defensive display trying to make itself look as big as possible and warning of a bite.
I don’t think there is any ambiguity in the intention of this female Veiled Chameleon. She has gone past the defensive state and jumped with to the offensive. There is no warning about an incoming bite. She is actively search to a target to bite.