What's the difference between the "-ism" and the "-istry" suffixes?

Question

So, the "-ist" suffix is used to denote a person who is related to the word or word root that the "-ist" suffix is attached to (e.g. practicing that profession, adhering to that philosophy, etc.)

However, when you want to convert it into a noun that describes the pursuit that the "-ist" suffix person is engaged in, sometimes you use the "-ism" suffix, and sometimes you use the "-istry" suffix - a dentist is a person who engages in dentistry, a sophist is someone who engages in sophistry, a terrorist is someone who engages in terrorism, and an antagonist is someone who engages in antagonism.

Why do some of these words use the "-ism" suffix, and some use the "-istry" suffix? Is it something to do with the etymology of the word roots, is it some subtle grammatical or meaning difference, or is it just one of those inconsistent things that the English language does sometimes? I just tried looking on Google, and I can't find anything useful.

Answer 1

-istry should not be interpreted as a suffix itself, as it's both -ist and -ery.

-ism

1 : a distinctive doctrine, cause, or theory

2 : an oppressive and especially discriminatory attitude or belief

-ist

a suffix of nouns, often corresponding to verbs ending in -ize or nouns ending in -ism, that denote a person who practices or is concerned with something, or holds certain principles, doctrines, etc

-ery

a suffix of nouns denoting occupation, business, calling or condition, place or establishment, goods or products, things collectively, qualities, actions, etc.

To answer your question, the distinction would be that -ism would denote a system, or in the given "Terrorism" denotes some ideology. And -istry correspondingly an occupation.

Answer 2

"…ist" describes one who acts or practices

"…istry" describes the activity or practice in general

"…ism" describes a specific act or belief or, perhaps, the practical effect of either.

Much of the problem is that many acts, beliefs or fields simply do not suit all three grammatical parts, any more than "…ics", "…istry" or "…ology" work for any given field of study, as "chemics/ology", "electristry/ology" or "vulcanics/istry", let alone "humanities".

I suggest that whether "…ics" or "…istry", "…ities" or "…ology" describes a practice, science or belief is historical, influenced by whether the idea has its roots in Greek or Latin, German or what - and let's remember that physics, mechanics and many other fields use neither "…istry" nor "…ology"