The spelling of 'filtration' and 'disastrous'

[Mehrgan]

Is there any rule or title for the list of words with different spellings for verb and noun modes? I am looking for a possible reason why 'e' has to be dropped in such spellings.

Filter >> Filtration
Disaster >> Disastrous

 

[Barque]

Is there any rule or title for the list of words with different spellings for verb and noun modes?

No.

I am looking for a possible reason why 'e' has to be dropped in such spellings.

The e isn't always dropped. Bother and botheration. Flatter and flattery.

A possible reason is that dropping the e also takes away a syllable and makes the word easier to pronounce. Another possible reason is that that's just the way it is.

Filter >> Filtration
Disaster >> Disastrous

Though you refer to "verb and noun modes", only the first pair is a verb and a noun, while the second pair is a noun and an adjective.
Filter can also be a noun, though as a noun it doesn't mean the same as filtration. Bother is also both a verb and a noun, and as a noun it does mean the same as botheration.
Disaster is always a noun. Disastrous is an adjective, not a verb.

 

[Mehrgan]

No.

The e isn't always dropped. Bother and botheration. Flatter and flattery.

A possible reason is that dropping the e also takes away a syllable and makes the word easier to pronounce. Another possible reason is that that's just the way it is.


Though you refer to "verb and noun modes", only the first pair is a verb and a noun, while the second pair is a noun and an adjective.
Filter can also be a noun, though as a noun it doesn't mean the same as filtration. Bother is also both a verb and a noun, and as a noun it does mean the same as botheration.
Disaster is always a noun. Disastrous is an adjective, not a verb.

Thanks, and yes I should've used 'parts of speech'. And still it confuses learners and words like these happen to be commonly misspelt.