This is connected to a question on BH-SE.
I have found a little in regard to the etymology of this word. For example, the root is obviously Sabbath. What significance does the greek ending "-ισμός" (-ismos) have?
I wondered if anyone here has any more particular/detailed insight than the Wiktionary offers.
Some specific questions: Does it self contain any indication of an article (definite or indefinite)? in other words, of itself would it be "a keeping of the Sabbath" or "the keeping of the Sabbath" or do words using an -ismos ending depend on the surrounding text for any article?
Would it be the equivalent of a deverbal noun or gerund in English? Would it be "keeping the Sabbath"
Does it maintain any number/gender from its root-- "(I keep the Sabbath)ing"
-ισμόςalso has an etymology on Wiktionary. Only for Modern Greek but it might be of interest to you. I also added an etymology request to the Wiktionary article of the full word for you. Anybody can do this by the way.