My grunt is dissed, but was I ever gruntled?

Some words are interesting. I've never understood why flammable and inflammable mean the same thing. But I just looked and apparently:

... However, in "inflammable," the "in-" comes from the Latin verb "inflammare" and acts as an intensifier, meaning "to cause to catch fire".

It seems you can also be capacitated, not just incapacitated.

Then there are words like take and mistake which aren't the same at all.

It is like some of it has just been made up ;-)

I asked why we have two prefixes to indicate a negative, in- and un-.

The answer seems ok, but makes my "inflammable" more confusing.

.

The prefixes "un-" and "in-" both indicate opposites, but their usage often depends on the origin of the base word. "Un-" is the Germanic version and is used with words of Germanic or Anglo-Saxon origin (e.g., unhappy, untrue), while "in-" is a Latin-derived prefix used with words from Latin or French (e.g., inactive, incorrect). 

"Un-"

Origin: Germanic.

Usage: Typically used with words that have Germanic roots. It can mean "not" or signify the reversal of an action.

Examples:

Not: unhappy, unlucky

Reversal of an action: unzip, untie 

"In-"

Origin: Latin.

Usage: Used with words that have Latin or French origins. It generally means "not".

Examples:

Not: inactive, incomplete, incorrect

Reversal of an action: undo (though this uses the Germanic "un-") 

Why two prefixes?

English is a language with many influences, primarily from Germanic and Latin roots.

As words entered the language, they often kept the negative prefix from their original language.

This is why words like unhappy (Germanic) and incorrect (Latin) both mean "not" but use different prefixes. 

I asked why we have two prefixes to indicate a negative, in- and un-.

The answer seems ok, but makes my "inflammable" more confusing.

.

The prefixes "un-" and "in-" both indicate opposites, but their usage often depends on the origin of the base word. "Un-" is the Germanic version and is used with words of Germanic or Anglo-Saxon origin (e.g., unhappy, untrue), while "in-" is a Latin-derived prefix used with words from Latin or French (e.g., inactive, incorrect). 

"Un-"

Origin: Germanic.

Usage: Typically used with words that have Germanic roots. It can mean "not" or signify the reversal of an action.

Examples:

Not: unhappy, unlucky

Reversal of an action: unzip, untie 

"In-"

Origin: Latin.

Usage: Used with words that have Latin or French origins. It generally means "not".

Examples:

Not: inactive, incomplete, incorrect

Reversal of an action: undo (though this uses the Germanic "un-") 

Why two prefixes?

English is a language with many influences, primarily from Germanic and Latin roots.

As words entered the language, they often kept the negative prefix from their original language.

This is why words like unhappy (Germanic) and incorrect (Latin) both mean "not" but use different prefixes.