Hippopotami and paninis
English contains more foreign loan words than you can shake a stick at. In some cases both their singular and plural forms have been adopted, but sometimes only one of these forms makes it into English. For example, panini is the plural of panino, an Italian-style sandwich, but only the former is normally used in English – the plural paninis is quite common. In Italian the plural of pizza is pizze, but in English we say pizzas.
Some, though not all, of the unusual plural forms are regularised. Examples include, stadium, the plural of which is either stadia, or more commonly, stadiums. Formula, which can be pluralised as either formulae or formulas. Also kibbutz – kibbutzim/kibbutzes; octopus – octopi/octopuses; hippopotamus – hippopotami/hippopotamuses; index – indices/indexes; matrix – matrices/matrixes.
A few years ago I went to Sicily for a holiday. On arrival in Catania I felt a bit peckish so went to get something to eat at an airport café. In some Italian cafés you have to pay first, then you take the receipt to the food counter and pick up your food. I asked the guy behind the cash register for ‘uno panini‘, thinking I was asking for one sandwich. As I used the plural form (I’d forgetten the singular), he thought I was asking for two and charged me accordingly. I was quite surprised when the food counter guy handed me two sandwiches, but didn’t mind too much as I was very hungry by then.
Here’s a plural-related conundrum (plural conundra/conundrums) for you: the plural of child is children, the plural of ox is oxen. Can you think of any other English words with the same type of plural?