But it is strictly correct. Deflagration is the definition of low (i.e. subsonic) explosive.
Combustion is a broader term — combustion just refers to burning. And the reason it is called an internal combustion engine is to contrast it from its predecessor combustion engine designs - the external combustion engine.
More precisely, the type of combustion happening in an ICE engine is (low) explosive.
But it is strictly correct. Deflagration is the definition of low (i.e. subsonic) explosive.
Combustion is a broader term — combustion just refers to burning. And the reason it is called an internal combustion engine is to contrast it from its predecessor combustion engine designs - the external combustion engine.
More precisely, the type of combustion happening in an ICE engine is (low) explosive.
https://en.wikipedia.org/wiki/Explosive#Low