The term 'Formicary Denizen' refers to two creatures that inhabit an ANT colony. The first creature is an ANT, which is a small, social insect that lives in colonies and is typically identified by its three-letter Latin name, 'ANT'. The second creature is an EMMET, which is a type of ANT that is usually five letters long and is also known as a 'pavement ANT'. Both ants and emmets are important members of an ANT colony, and they work together to ensure the colony's survival.