Rigid
Rigid turns up in 2 fields: electricians, aviation. Here is what it means to the people in each one.
Rigid in electricians
Heavy-wall threaded steel conduit, the toughest raceway on site, used for services, exposed runs and hazardous areas.
Rigid, formally rigid metal conduit or galvanised rigid conduit, is thick-walled steel pipe threaded on both ends with a tapered thread and joined with threaded couplings. It shrugs off physical damage, can be buried or encased in concrete, and is required in many hazardous locations and is the usual pipe for service masts. It is bent with hickeys and mechanical or hydraulic benders and cut and threaded on site, and it weighs noticeably more than IMC, its thinner threaded cousin.
"Service mast has to be two-inch rigid, thread it on the machine and set the weatherhead high enough to clear the drop."
Rigid in aviation
A type of airship that maintains its shape using an internal structural framework.
A rigid airship relies on a solid internal skeleton, usually made of lightweight metal or composite rings and girders, to hold its aerodynamic shape. Unlike blimps, which depend on internal gas pressure to stay inflated, a rigid contains multiple unpressurized gas cells enclosed within its outer fabric envelope. This design allows them to scale to massive sizes and survive punctures without immediately losing their structural integrity.
"The historic hangar was originally built to house rigids, which is why the ceiling clearance is so massive."