OPOSSUMS ARE MARSUPIALS. If you open just about any field guide to North American mammals, the opossum will probably be the very first of the 380 or so mammal species described. That's because opossums are our only marsupial, and marsupials are considered very ancient forms of mammals.
operator - an agent that operates some apparatus or machine; the operator of the switchboard. manipulator. causal agency, causal agent, cause - any entity that produces an effect or is responsible for events or results. company operator - an operator who works for a company. driver - the operator of a motor vehicle.
Operator was first used by Delta Force to distinguish between operational and non-operational personnel assigned to the unit. Other special operations forces use specific names for their jobs (Army Rangers, Navy SEALs, Air Force Pararescuemen); operator is the specific term for Delta's operational personnel. However, since the early 2000s other special operations forces have adopted the term.