Definition
An aircraft structure made of materials and built in such a way that it can perform its intended function under the heat conditions likely to occur in the location where it is installed, without failing structurally for a specified period of time.
Plain English
A part of the aircraft built so that if a fire breaks out near it, the part keeps doing its job long enough to matter — it doesn't fail right away when exposed to heat.
Context Anchor
Seen in aircraft construction, certification, powerplant-area design, and maintenance discussions about materials near possible fire sources.
Derivation
"Fire-resistant" means able to resist fire — to hold up against it for a time. It is deliberately a weaker term than "fireproof." Fireproof means the part can withstand fire as well as steel of the same thickness; fire-resistant means the part can withstand heat and flame for a useful period, but not indefinitely.
Why Pilots Care
Provides critical time for pilots to respond to fires by containing flames and preventing rapid structural failure that could lead to loss of control.
Intuition Check
Do not read fire-resistant as fireproof. Fire-resistant means it resists fire damage for a limited, useful time; fireproof would mean a higher level of protection.
Example Sentence 1
The engine cowling is built as a fire-resistant structure, so it will keep its shape long enough to contain a fire while the pilot completes the engine shutdown checklist.
Example Sentence 2
During certification, inspectors verify that all fire-resistant structures meet FAA standards before the aircraft enters service.