IPA: /ˈhiːtpruːf/
KK: /ˈhitˌpruf/
Not affected by high temperatures, often used to describe materials that can withstand heat without being damaged.
The heatproof pot can be placed directly on the stove without any risk of melting.
Heatproof → It is formed from "heat" (from Old English "hætu", meaning warmth or high temperature) and "proof" (from Old English "prūf", meaning resistant or tested). The word "heatproof" means resistant to heat or able to withstand high temperatures without damage.
Think of something that is 'resistant' ('proof') to 'warmth' ('heat') — that's why heatproof means it can withstand high temperatures.