Effectively, yes. こと is extremely versatile as a nominaliser (i.e. something to turn a phrase into a noun phrase), and it gets stuck on the end of a lot of dictionary definitions for nouns, usually appearing after verbs or adjectives. The other major word that does this job in dictionaries is さま, though in that case, the focus is on overall appearance or… state, I guess? さま is about how something is or looks; it’s about a description. こと tends to be more of a concept or action i.e. it’s more about ‘what’. And yes, it’s often a headache to translate because it’s used in a lot of ways we wouldn’t use, say, ‘act’ or ‘fact’ in English e.g.
ダイエットしたいなら、甘い物を食べないことだ
If you want to go on a diet, you have to/it’s gonna be all about not eating sweet things
(I got that from here because I just couldn’t think of a simpler example, and I was worried I’d come up with some unnatural rubbish.) In essence, that usage is about stating the most important thing for a particular purpose/with regard to a particular topic (at least, that’s how I understand it), and is usually used for giving advice, prohibiting things etc. Indeed, no literal translation of that would be natural in English.
I guess you could see it that way? I’m a native speaker of Chinese and English, and my grammatical understanding of Chinese is actually a little poorer than what I know for English, but the thing is… as much as Chinese dictionaries do indicate parts of speech for everything (e.g. ‘this is an adjective, verb, noun etc.’), in practice, Chinese is very flexible. For example… (OK, I had to go hunting for this because I couldn’t think of something more natural on my own)
这本书的出版
The publishing of this book
出版 is a verb in Chinese. However, functionally, at least from the perspective of the sort of grammar we’re used to, it’s clearly a noun. Chinese doesn’t really care. The paper in which I found this example said,
既然汉语里几乎所有的动词都可以出现在“N的V”的格式里，都可以作主宾语，那就只需将这一特性归为动词的特性 […]
Since in Chinese, just about all verbs can appear in the ‘Noun [reversed “of”, like の] Verb’ format, and can all be used as subjects and objects, then this particularity just needs to be classified as a particularity of verbs […]
So yeah, it’s a verb. For that matter, I went and checked earlier, and actually, 受 and 託 are both verbs in Chinese. But because we can just as easily treat verbs as nouns equivalent to the action the verbs describe… I guess Japanese adopted that behaviour as well. Of course, there are contexts where this feels a little unnatural, but it’s very much a possible construction in many other circumstances.
EDIT: Just to clarify, in Japanese, you usually have to turn the noun into a verb with する, and that’s what happens in most cases. However, there are also instances, especially in formal contexts, where する just gets omitted and you simply see を[suru-verb stem], because it’s clear that an action is being done. Why exactly this usage exists, I don’t know, but it does appear in the news, at any rate.
(But thanks, this looks like a very good tool for exploring words) They help paint a picture about its stem meaning, if you get what I’m talking about. I don’t see it alone there. Which is what i’ve been complaining about since the start. WK vocabulary is words (unless it uses a specific ~stem~ pattern). 受託者 is a word. I totally understand it. It means trustee, it should have been the vocab entry.