Single word meaning last of two

When you have two items, the first item is simply the first item. However, the second item implies there might be more after it, and the last item doesn't tell you out of how many.

Is there a single word that means both last and second, or last of two?

A is the first item.
B is the ___ item.

Other is no good, as it is usually paired with one and it also doesn't specify an order. One could be A or B, in which case the other one is B or A.

I'm working with something like an ordered pair, but it's not obvious that it's a pair of items. It's to do with words regardless of the language, and in Semitic languages, the left word is the second word and the right word is the first word, whereas in English the order is the reverse of that.

• Would that this were the Lisp programming language, where car and cdr are the terms of art. :)
– tchrist
Commented Jul 8, 2018 at 15:55

You “can’t” say that something is “the last of the two”. That’s because you are not “supposed” to use the superlative degree with only two items. You are “supposed” to use the comparative degree.

The comparative degree of last is simply latter, which is the word you are seeking here.

A would be the first or former of the two, and B would be the second or latter of the two. You “can’t” say that something is the last of the two.

It’s just like when you have two friends of differing ages. One is the older of the two, never the oldest of the two.

You should be aware that this is to some extent a matter of register, and that making this sort of distinction may be thought by some to be “too fancy” for common use. But in educated registers, it still holds true.

If you only have two items, and you've specified that, then you're making a false assumption that the second item implies there might be more. With a stated number of two, the second number, by definition, has to be the last. (Barring future events if last is being used temporally.)

Also, the word first has two different meanings. It means the item's xth position and it also means that it's the item in the initial position.

So, there are two valid comparisons:

1. A is the first item and B is the second item.
2. A is the first item and B is the last item.

Don't be confused by the fact that in each of those comparisons, first is being used in a different sense.

If you want to be explicit about both of these things—if, say, you haven't already specified the number of items in a list, then the following would be used:

1. With only one item, A is the first and only item.
2. With only two items, B is the second and last item.

There is no single word that can be substituted in either case that means exactly the same thing in all contexts.

Note that in a list of multiple items, it's also possible to say that A is the first and initial item. But, even though correct, it sounds a bit strange and such meaning is normally understood in context.

When you have two items...

Your initial phrase defines the total number of items as two. Therefore, the terms first item and second item denote their ordinal positions as `1 of 2` and `2 of 2`.

Since the contentions in your second sentence are absent any recognition that the total number of items is already known, they are logically hollow. That can be easily remedied by revising the opening phrase to obviate any information as to the cardinality of the set:

When you have a number of items, the first item is simply the first item.

With this change, the first item is now in position `1 of ?`, the second item in position `2 of ?`, and the `last item` would be `? of ?`, making the contentions in your second sentence perfectly true:

• A is the first item.
• B is the second item. (But it may not be the last)

and

• A is the first item.
• B is the last item. (Of an unknown number)