This keeps confusing me. I keep imagining "permittivity" as being "The ability for a substance to permit electricity", when it is the opposite. High permittivity means it is hard (requires a lot of charge) for electric fields to be produced, while low permittivity means it is easy. I can't find the etymology on the internet.
Although it's not a traditional English word, I keep hearing it like it's just a normal English word and deducing "ability to permit" just like "morality" or "similarity". High "A-ity" meaning more A/easier to do A.
The inverse doesn't make much sense, such as more permittivity => more charge, as the field doesn't create the charge - the charge creates the field.