Word of the Day - Poset

poset

/ˈpəʊsɛt/
noun
Mathematics
A set whose members exhibit partial ordering.

Origin
1940s. From the initial letters of partially ordered + set.

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Bob counted, "one, two, three, four..." and his friend, Sandy, a math teacher, commented, "You are giving an example of a poset, albeit one which is also a totally ordered set."

As you might also suspect, the conversation did not go much further since Bob has very limited skill in math. But Bob did later consult Wikipedia, hoping to be able to sound smarter than he is when he next saw Sandy.
He found out that geneology charts are a good example with some, but not all, relationships being ancestral, hence, partially ordered.