mumpsimus /mumpˈsi-məs/

1. A view or opinion stubbornly held, even when shown to be misguided
2. A person holding such a view, or one adhering stubbornly to old ways

• left-hander
• left-handers
• left-handiness
• leftie
• lefties
• leftish
• leftism
• leftisms
• leftist
• leftists
• left-leaning
• left-luggage office
• left-luggage offices
• left-of-centre
• left-off
• leftover
• leftovers
• left, right and centre
• lefts
• leftward
• leftwardly
• leftwards
• left wheel
• left wing
• left-wing