We say that a set $X$ (maybe class, I don't know) is saturated or is complete if for every $Y\in X$, $Y$ is a proper subset (maybe proper subclass?) of $X$: $$ Y\subset X $$
An example of a complete subset is any ordinal. However, I can't imagine ''how'' is an ordinal. So, can you give me an explicit set that is complete?
For example, I think $1=\{\emptyset\}$ is complete, since their unique element is the $\emptyset$ that is also a proper subset. I have also tried with $2=1\cup\{1\}=\Big\{ \emptyset,\{\emptyset\} \Big\}$, and again $\emptyset\in 2$ and it is also a subset and, since $\emptyset\in 2$, $\{\emptyset\}\subset 2$.
At this point I suppose every natural is a complete set, since ordinals are a generalization of naturals. So can give more examples rather than naturals?
Addeundm. Thanks to @AndreasBlass for indicates my mistake.