Why do “flammable” and “inflammable” mean the same thing, or is there a difference?

Question

Edit: SERIOUSLY, THANK YOU—

BTW my confusions stems from them having the same meaning online

Flammable: “easily set on fire”
Inflammable: “easily set on fire”

Definitions from Oxford Languages

In: Other

Answer 1

The issue is that the prefix “in-” has two different meanings. It is most commonly known as meaning “not” as “inaudible” (in- audi -ble, “not able to be heard”). But it also means “in, into” in such words as “inquiry” (in- query, “ask into”).

So here, “inflammable” isn’t meant to be parsed as in-(flammable) as in “not able to set on fire” but rather (inflamm)-able as in, “able to be inflamed.” After all, you might have heard the word “inflame” and understand it to meant to set something on fire or to make a fire bigger. (Where inflame comes from in- flame with “in-” taking on the second meaning, e.g. “to put into flames”).

EDIT:

If you, too, are interested in how things like this come about, an INvaluable resource is the [Online Etymology Dictionary](https://www.etymonline.com/).