'Ansible' seems to be something of a nonce word, coined by Ursula le Guin for use in a 1966 novel and then used by her again in later novels.
In this it's a little like the 'babel fish' in the Douglas Adams 'Hitchhiker' novels; this device, when inserted in your ear allowed you to understand any kind of spoken language. This term was later used by Yahoo for a free online translation service.
Another example of such a word is 'Floo powder' in the works of J.K.Rowling, which allowed Harry Potter and co. to travel around by using people's chimneys!
The Wikipedia page for 'ansible' claims that 'the name of the device has been borrowed by numerous authors'.
Numerous? It quotes only one, somebody called Orson Scott Card, with whose works I am unfortunately not familiar.
The article goes on to claim that 'Numerous (again!) other writers have included faster-than-light communication devices in their fictional works' . It doesn't, however, make it clear in just how many of these, if any. the device in question is called 'an ansible'. In at least one of them, 'Gridlinked' by Neal Asher, the device is named runcible not ansible.
In the only one of the works quoted which I have read, The Amber Spyglass by Philip Pullman, I certainly can't recall any reference to something called 'an ansible'. Lyra, the heroine of the novel, is able to make instant contact with a witch friend of hers by holding a piece of 'cloud pine' and calling the witch's name, but this is a form of supernatural power rather than a scientific device of the kind found in science fiction.