From my understanding (and Wikipedia agrees with me[1]), "outsourcing" simply means paying someone to perform work outside your company that the company would otherwise perform. For example, my employer outsources payroll to ADP, and outsources office cleaning to a service company rather than hiring its own cleaning staff.

[1] https://en.wikipedia.org/wiki/Outsourcing - "In business, outsourcing involves the contracting out of a business process (e.g. payroll processing, claims processing) and operational, and/or non-core functions (e.g. manufacturing, facility management, call center support) to another party."