Irregular plural nouns – foreign plurals

hello grammarians today we're talking about another kind of irregular plural noun and that is the foreign plural those are words that are borrowed into English from some other language words like fungus or cactus or thesis or criteria and these words come from Latin and Greek respectively but don't get the idea that you need to learn to be able to speak Latin or Greek in order to speak English no not at all but while some words that got borrowed into English have lost their language specific plurals some have not some have maintained those plurals and it kind of depends on which situation you're using them in so for example in an informal context it would be perfectly acceptable for you or me to say funguses like that but if I was talking to a biologist she would probably say fungi if she were talking about them in a scientific context just like it's okay in informal speech to talk about cactuses you're driving a long road in Arizona you see a lot of cactuses but again if you studied cactuses for a living you would probably call them cacti it's more precise it's more formal if you like it's more polite now my feeling is that as fungus and cactus get more and more entrenched into English eventually these formal endings are going to fall away and we're just gonna have this regular plural but for now there are still some pluralizing rules for other languages that it helps to know so let's go through those so I made this little chart to go over the six most common Latin and Greek irregular plurals that you're going to encounter in English so the first one is final a to final AE so you take a word like larva in the singular which is like a little baby bug like an ant larva or a caterpillar larva and the traditional irregular plural the Latin plural of that is larvae AE but the regular plural that will probably get more popular over time as larvas but this is the first one a to AE larvae to larvae just like antennae becomes antennae secondly the ending change from final us to final I which we find in a word like fungus is the singular and then the irregular plural of that is fungi and as I said before there are some people who use funguses but again that regular plural is more informal this next one is also Latin and it's the change from final um to final a so we take a word like datum which is a single unit of data so the plural of data so we change singular datum to plural data and there is no accepted you wouldn't say that data's that is not an accepted regular plural I think what's going to happen instead is that datum is gonna fall away but again it hasn't really happened yet not in a not in a formal context anyway this next one is also Latin and its final e^x or final IX - final icees so if you take a word like index or matrix the plural of that is not indexes but indices indexes is again the informal regular plural but indices is the more formal irregular plural likewise matrices this one is Greek and it's the change from final is to final es as in the word thesis in the singular becoming theses in the irregular plural the regular plural this I do not care for because it is thesis --is and I think that sounds silly but thinking something as silly is no reason to stand to thwart the tide of linguistic change grumble grumble this last one is also Greek and it's the change from singular Oh n to plural a so we take the this word like criterion or phenomenon and in the plural it is criteria or phenomena do-do-do-do-do and as with datum there isn't really a regular plural form for criteria nobody says criterions because the word criteria is so much better known anyway so these are six little ending rules like I said you don't need to learn Latin or Greek in order to make sense of English but having these six rules in your tool belt if you use them judiciously will probably come in handy but for real if you see a word and you don't know its derivation just trust your instincts and give it a regular portal just tack on an S you know the world's not gonna end no harm will come to you and if you're curious you can look it up later you can learn anything Dave it out