When you see “combustible” on an MSDS, it has a specific meaning. We normally think of “combustible” as meaning “catches fire easily.” But in regard to liquids in MSDS lingo, the meaning is different. It means the liquid is “flammable” (can ignite) if heated to 100°F. If “combustible” is missing from the MSDS, don’t assume it means the liquid can’t burn.
A related term is “flammable limits.” This applies to gases and vapors. There’s the Lower Flammable Limit (LFL), below which the mixture is too lean to burn. And there’s the Upper Flammable Limit (UFL), above which it’s too rich to burn. If you’ve ever tinkered with adjusting a carburetor or have had to open the choke on a 4-cycle engine to keep it from stalling, you have an understanding of what these limits mean.
Another related term is “flashpoint.” This is the temperature at which a liquid produces enough vapor for ignition to occur.