Oldest/eldest?

[LackingInspiration]

Which one is right and why?

I think either is correct - provided you are comparing more than two things! I have to contain my ire when I hear people referring to "my eldest" and "my youngest" when they only have two children. Even though I can accept it would sound massively poncey to say "my elder child" and "my younger child".

I think that both are correct but elder is an older (arf) usage. I am away from home so I don't have access to any reference books, but my hunch is that elder/eldest is an archaic form.

Also note that elder/eldest/elderly tends now to be used only in conjunction with people (village elders, the eldest son, elderly relatives etc) whereas older/oldest/old is more used for inanimate objects (use that orange juice first, it's older - I've got the oldest car on our road - an old house).

Eldest.....when between two DC
Oldest.....when there are more than two.

I think!

No, it's nothing to do with the numbers.

They are alternate forms of the same word.

You can say "he is the eldest son" when there are 2 sons or 12 sons. It doesn't matter.

However you can't say "that is the eldest book I've ever read". At least, it would be a highly unusual form these days.

So it's ok to say 'my oldest daughter' or 'my eldest daughter' but you can only say 'my oldest book [or other object]'?

Right... so it's not comparative/superlative then!

Well spelling and grammar were never my strong point!

Lackingininspiration - basically yes.

Notagranny yet - no, nothing to do with comparative/superlative I'm afraid

Elder/Older are comparatives.

Eldest/Oldest are superlatives.

I think it's probably something to do with the etymology of the word because the Old English word for Old was Eald, so I think this probably becamee Old in most senses, except in some specialised cases where it retained the E. That's just my guess though, as I can't look anything up!

theyoungvisiter: Eldest/oldest is the superlative, so should be used when there are 3 or more. If two, one would use the comparative - elder/older.

The comparative form gives a clue: it's more natural to say "elder" when talking of children, so "eldest" might be preferable. Though I think that in the superlative they are interchangeable.

It gets more complex if a sibling is deceased, so the oldest child is not the eldest (if it is intended to refer to first born, who if still living, would also be the oldest).

Or why the younger son is now the oldest, and why the apparently younger of two in the current family is also the youngest child.

Onimolap that's incorrect - you can use the superlative even when there are only two possibilities.

For eg you can say "These are my best shoes" even when you have only two pairs.

The difference is that if there are only two possibilities you can use EITHER the superlative OR the comparitive. If you have two children you can say "he is the elder" or "he is the eldest" - either is correct.

comparative

I can spell honest. My nickname is a witty joke.

[scrabbles to retain place in pedants' corner]

Youngvisiter: I don't think so. The phrase you cite is an idiom, akin to "Sunday best" ie better than all (plural) the rest (whether there is one or more current example of any others) hence superlative.

It's like the difference between "she's better at spelling" (better than the state (singular) before or than one other person), versus "she's best at spelling" (better than at other activities, or than other people (plurals).

Even if Child B is older than Child A, Child B still might not be the oldest in the family.

Onimolap I disagree - it's not to do with number - it's a simple question of meaning. You can use a superlative to mean the highest example of something regardless of the number of competiters. For eg you could quite correctly say:

"Sebastian was the tallest boy in his class. The fact that he was also the only boy in the class did not detract from his pride in this fact."

The rule of three or more is a simple teaching method for learners (particularly people learning English as a foreign language) to help them understand the graduated nature of adjective/comparative/superlative. This is particularly important for non-native speakers because romance languages mostly don't have separate words for comparative and superlative, so it's the same construction for comparative/superlative - "Elle est plus belle/elle est la plus belle"

The rule of three helps to underline the difference between "more beautiful" and "most beautiful" in English. However there is nothing incorrect in a native speaker saying that something is the most beautiful out of only two examples.