Because your comparison is not valid.

Both words mean the same; the original usage was from the verb inflame. The origin of that is Latin: inflammare: 'into flame'.
Consider the evolution to inflammation (medical term.)

The confusion over the possible negative interpretation of the prefix in lead to the use of the shorter flammable in the early part of the 20th century, proving that, regardless of what the dictionaries like to sell, grammar and lexicons evolve and change very quickly.



It's another example of why we should all learn Latin.

innit?

regards

Sue

I tend to agree with Scribe...

If the plural of mouse is mice, then the plural of rat is rice?

CJSL

Crunching for a brighter future...

Those are sorta sticky and debatable, but I sometimes also get hung up on:

If the plural of goose is geese, then why can't the plural of moose be meese?

CJSL

Crunching like there is no tomorrow...

Of course you could give the person a flog of sheep (OFL)

Collective nouns spread with the availability of cheap printed matter in the late 15th century, mostly as a literary device.

Murmuration is late Middle English: from French, from Latin murmuratio(n- ), from murmurare to murmurâ.

In 1492, just before he died, the printer William Caxton moaned that England had so many dialects that even 50 miles outside London people could not understand each other. A Londoner trying to buy eggs in Colchester would need to ask for 'eises' or 'egys', depending how far east he was.

This was despite five hundred years of the unifying effect of French and Latin books on the English population, who stuck fiercely to their Flemish-German-Scandi dialectical roots.

Back to the meeces.