This is where I recently came across this very rare word:
If it was hard being a small boy in a time of rapid change, it was a doubly hard burden to be a meter-tall rabbit cursed with human sentience and cunicular instincts.
Singularity Sky, by Charles Stross, 2003. It would take too long to explain the background to this Carrollian image (the rabbit does have a waistcoat, but no pocket watch is mentioned).
It’s better known to biologists than to SF authors. It simply means “rabbit-like”. It derives from Latin cuniculus, rabbit (itself taken from Green kyniklos), which is also the source of the old English name for the animal, coney or cony. The Latin word could also mean a burrow, an underground passage, or a military mine. Variations on it appear in systematic scientific names — an American owl, to take one example, is formally known as Speotyto cunicularia because it lives in burrows.
Cunicular has occasionally been used in botany and medicine for various kinds of tubular formation. Apart from that, sightings are extremely rare.