Why is "lens" singular and "lenses" plural? Why isn't "lens" the plural of "len"?

@Callmyname I'm sorry -- I should have been clearer. the plural of the Latin noun is lendes. You are right that the plural of the English noun is lenses.

@Callmyname Well, I cannot be held responsible for the way the Roman empire communicated! 😃.

But English is a Germanic language that was heavily influenced by Latin, via French, after the Norman Conquest. So the real question is, "why does English form plurals the way it does?" I think the answer is "because French does it that way."

As for the "d", the word "lens" in Latin is a third declension noun. As is often the case with nouns of the third declension, it is the nominative singular that is the exception. In other words, all the other forms of this noun do have a "d.".

For example: genitive singular, lendis (of the lens)
accusative singular: lendem (when the noun is used as a direct object)
nominative plural: lendes (when the plural is the subject of the sentence.)

The list goes on and on. The only case in which the "d" is missing is the nominative singular (when the singular noun is the subject of the sentence". The "d" disappears, and we just get "lens" instead of "lends"

You're probably more familiar with this with other Latin nouns. For example, the second declension noun "alumnus" has the plural "alumni", not "alumnuses". The first declension noun "alumna" has the plural "alumnae".

Latin has 5 noun declensions, each with its own set of rules about this!

@Callmyname Well, as it says on a tee shirt that my wife got me as a present: "Id est quod id est!" (It is what it is!)

I find Latin fascinating. I started studying it on my own a few years ago, simply as a hobby. (Yes that is nerdy,but so am I! lol)

@Callmyname No, I went to an engineering school in the 1970's. The word "nerd" was very common, long before it got used in movies. But the word has changed. It used to mean "someone who likes studying math and science a lot" (with the comic implication that that makes us socially inept!). Picture the guy (and the image was usually male) with thick glasses, a white shirt, a pocket protector with lots of pencils, a slide rule attached to his belt (no calculators yet) who loved spending hours working on computer programs and solving calculus problems. That's the original meaning of "nerd."

@Callmyname Oh, I understand :)

I was mainly pointing out that the word is older than the movie usages.

And those of us who were called nerds took it in good humor. We turned the word around and embraced it, so that it no longer was an insult.

@Callmyname Okay, I am just not insulted by being called a nerd, which is why I referred to "nerdy" activity. Where you are, the word apparently has a more pejorative meaning.

Now, if someone was actually trying to be mean and used the word in that kind of tone of voice, that is different. But such a person could use ANY description of me in a threatening tone. Suppose someone started physically attacking me and calling me an "American." That would not make the word "American" an insult, even if the tone were insulting.

And that is how I feel about the word "nerd". I never, never use it to insult anyone.

@Callmyname yes, that is my point. A word can be neutral, but a hateful person can use it as an insult. The hate is in the person, not in the word.

@Callmyname There is nothing neutral about that word, as far as I can see. At least not nowadays. I can imagine how originally, it might have come about merely as a result of pronouncing the Spanish word for black, "Negro", with an American Southern accent. But today, no one uses the term with that kind of innocent purpose.

@Callmyname That is a very good question. I tend to draw the line at the distinction between what a person IS versus what they DO. I would never throw around ethnic insults. But, if there is trust between two people, they can kid each other about their interests, their tastes, etc.

Engineers and mathematicians tell jokes about each other all the time. The stereotypes are that the mathematician is abstract but absolutely impractical and doing anything "real", whereas the engineer is practical but unimaginative. Now, those could be hurtful attitudes. But since both professions really do respect each other, we all laugh, regardless of which of us are the butt of the joke.

Well, I am a mathematician, and I laugh at jokes that poke fun of mathematicians.

Not as rare as you might think. But, clearly we will always disagree about this.

I appreciate being able to have a spirited discussion here, without resorting to name-calling and insults. Thank you.

I agree. And I am saying that I appreciate that. So many other disagreements on SW do seem to degenerate into that. So again, thank you for an honest, spirited, respectful discussion.