[chrisheltra]

Here's the wiki definition but I know the term is more widely used now.

Inside the United States Special Operations community, an operator is a Delta Force member who has completed selection and has graduated OTC (Operators Training Course). Operator was first used by Delta Force to distinguish between operational and non-operational personnel assigned to the unit.[21] 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.

SEALs may have unofficially referred to themselves as operators since the Vietnam War. Author and Navy SEAL Gene Wentz makes many references to fellow SEALs as operators in his 1992 book titled "Men In Green Faces," which is about the SEALs in Vietnam.[25]