A formicarium is a habitat for ants kept in captivity. There are several synonyms for the word. One synonym is ant farm, which is a transparent plastic or glass container with sand, soil or gel where ants can tunnel and build colonies. Another synonym is formicary, which means a structure built by ants in their natural habitat. An ant nest is another synonym for formicarium, which can either be a natural habitat or a man-made structure for ants to live and multiply. Lastly, an ant habitat is also a synonym for formicarium, which can have various designs and shapes to keep ants in captivity.