IPA: /ˈtʃɑːrtərər/
KK: /ˈtʃɑrtərər/
A person or company that hires or leases a vehicle, such as a ship or aircraft, for a specific period of time.
The charterer arranged for a yacht to be available for the summer vacation.
Charterer → It is formed from "charter" (from Old French *chartere*, meaning a written document or grant) and "-er" (meaning a person who). A charterer is a person who holds or uses a charter, typically in the context of leasing a vessel or vehicle.
Think of a 'charter' as a written agreement, and the '-er' indicates a person involved with that agreement. So, a charterer is someone who uses or holds a charter.