Generally the "1st/2nd" bit denotes how many generations up you have to go to find a common ancestor, and "removed" is how many generations removed the other person is from that generation.
You are, to your your first cousin's child, who is your first cousin once-removed, a second cousin once-removed.
Actually the term "second cousin" does not have a concrete meaning. It can mean a true second cousin, or it can also mean a generation removed from a first cousin. The "once removed" terminology was introduced to compensate for this ambiguity.
Ah, I read "sons of first cousins" as "two people who are first cousins to each other each have a son". "A son of a first cousin" would be much less ambiguous. In fact, even knowing what you meant, I have a hard time reading the meaning you intended to convey.
Another clearer way to phrase it would be "sons of my first cousin are not my second cousins".
That makes a lot of sense! The distinction between sibling and nth cousin is basically arbitrary. (Although obviously there is logic in making the distinction as well as in omitting it.)
brother b1 and sister s1 from family 1, with parents g1
brother b2 and sister s2 from family 2, with parents g2
s1 has child x with b2 - x has grandparents g1, g2
s2 has child y with b1 - y has grandparents g1, g2
x and y are cousins, and also share the same 2 pairs of grandparents :-)
Those are "double first cousins". I even have some triple cousins in my tree, where three siblings from one family married three siblings from another family.
Agreed: in the case of siblings you share all ancestors; with cousins only some. In that way the distinction makes sense. The other way to look at it though is that with siblings your common ancestor is one generation up. With first cousins, it's two. With second, it's three. So it's the same thing, just a matter of degree.
Worse even, the "once removed" notation has no notion of direction, so it's inherently ambiguous. I'm also pretty sure that less half of the people I hear using it know what it means (or tries to mean).
This got me confused. You actually mean people who confuse "second niece" (i.e. your cousin's son) with "second cousin". Is that usage common in english? The daughters of cousins are second cousins,no?
You are hitting the borders where logic and common usage meet.
I am actually surprised that descriptive grammar holds up so well to logic. (There's no a priori reason why descriptive grammar, that describes common usage of language, actually is as mostly compressible to simple rules as it is.)
Design of language is a constant trade-off, between ease of remembering, compression (ie giving shorter ways to express more common concepts), fault-tolerance, desire of the speaker to look clever, fashion, ...
And all of us work on the evolution of language every day.
That depends on which direction the cousin is removed. If a generation above your father, it is your first cousin twice removed. If a generation below, it is your second cousin.
You are a (1,0)-child to your father (who is a (0,1)-parent to you). Your father is either (2,3)-cousin or (3,2)-cousin to the other person. It is ambiguous from the terminology. So you are either (3,3)-cousin or (4,2)-cousin to them. That is second cousin for the former and first cousin twice removed for the latter.
I think, if your father's cousin-once-removed is a generation below him, then he/she is your first-cousin. While a generate above you father would signal first-cousin-twice-removed...
.png){kind=link}
I'm glad you linked to this Wikipedia article that proves I'm not mad into thinking there is a simple logic pattern that can be applied to cousinship.
However, this "once removed" notation is crazy. Why not second-uncle for parents of second-cousins and so on?