To make regular nouns plural, add ‑s to the end.
Cat – cats
House – houses
If the singular noun ends in ‑s, add ‑es to the end to pluralize it.
Truss – trusses
Bus – buses
If the noun ends with ‑f or ‑fe, the f is often changed to ‑ve.
Wife – wives
Wolf – wolves
Exception: roof – roofs
If the singular noun ends in ‑y, change the ending to ‑ies.
City – cities
Puppy – puppies
If the singular noun ends in ‑o, add ‑es to make it plural.
Potato – potatoes
Tomato – tomatoes
If the singular noun ends in ‑us, the plural ending is frequently ‑i.
Cactus – cacti
Octopus – octopi
If the singular noun ends in ‑is, the plural ending is ‑es.
Analysis – Analyses
Ellipsis – Ellipses
If the singular noun ends in ‑on, the plural ending is ‑a.
Phenomenon – phenomena
Criterion – criteria
Irregular nouns should be checked in the dictionary because they follow no specific rules.
Child – children
Goose – geese
Man – men
Some nouns don’t change at all when they’re pluralized:
You need to see these nouns in context to understand whether they’re singular or plural.
Mark caught one fish, but I caught three fish.