 Irregular plurals of English nouns from espressoenglish.net. To make the plural of regular nouns, we simply add S, for example, wall, walls, ski, skis, cat, cats. For nouns ending in the CH, SH, X, or S sounds, we add ES, for example, switch. Switches Brush Brushes Box Boxes Address Addresses The one exception is when the CH at the end of the word is pronounced like a K, for example, stomach, stomachs. For nouns ending in Y, we change the Y to an I and then add ES. For example, baby, babies, army, armies, puppy, puppies. For nouns ending in the F sound, we change it to VES in the plural. For example, knife, knives, wife, wives, half, haves, self, selves, wolf, wolves, and leaf, leaves. As for nouns ending in O, we can make the plural by adding S or ES. It depends on the word. Here are some words that always have ES in the plural. Potato and potatoes, tomato, tomatoes, hero, heroes, torpedo, torpedoes, echo, echoes. And here are some nouns ending in O where the plural is formed by simply adding S. Stereo, stereos, memo, memos, solo, solos, zoo, zoos, studio, studios. With some nouns ending in O, we can form the plural both ways. For example, ghetto and ghettos that can be spelled with S or ES at the end. Mango and mangoes, motto and mottos, tornado and tornadoes, tuxedo, tuxedos, volcano, volcanoes. Here are some nouns that look plural but take a singular verb. News, the news was so depressing. Gymnastics, gymnastics is great for getting in shape. Economics and mathematics, economics is quite difficult. Even though these nouns end in S, they are actually singular. Now here are some nouns that appear singular but take a plural verb. Pants, these pants are too small. Scissors, where are the scissors? Glasses, when I last saw your glasses, they were on the table. Each of these words, pants, scissors and glasses refers to a single object, but they take the plural form of the verb. Finally, we have the very irregular nouns. For example, man, men, woman, women, child, children, person, people, tooth, teeth, foot, feet, vertebra, vertebrae, mouse, mice, goose, geese. Some nouns do not change, their singular and plural forms are the same. For example, one sheep, two sheep, one deer, two deer, one fish, two fish, one series, two series, one species, two species. Some words coming from Latin or Greek have singular forms ending in US and plural forms ending in I. For example, alumnus and alumna are the singular form and alumni is the plural form. Cactus, cacti, fungus, fungi, nucleus, nuclei, stimulus, stimuli. Other Latin or Greek words have the singular form ending in IS and the plural form ending in ES. For example, the plural form of analysis is analyses, crisis, crises, diagnosis, diagnoses, hypothesis, hypothesis, oasis, oases. We also have Latin or Greek words ending in UM or ON, whose plural forms end in A. For example, one bacterium, many bacteria, criterion, criteria, curriculum, curricula, datum, data, millennium, millennia, phenomenon, phenomena. To learn Advanced English Grammar, check out the Advanced English Grammar course at espressoenglish.net. This course is for more experienced students who want to master the advanced details of the English language. It also includes personal feedback on your written English. Visit espressoenglish.net for the Advanced English Grammar course, which will help you take your English from good to great.