Many English nouns ending in -o form their plurals by simply adding -s. This page focuses on that straightforward pattern and provides a handy reference table showing singular and plural side by side. Use it when writing, editing, or teaching to check common words quickly. While plenty of -o nouns take -es, the entries below are the ones that standard usage treats as regular -s plurals. Because English is full of exceptions and style preferences, some words can appear with either ending. When in doubt, consult trusted dictionaries and style guides, but start here for the widely accepted -s forms.
| Singular | Plural |
|---|---|
| avocado | avocados |
| auto | autos |
| bamboo | bamboos |
| banjo | banjos |
| bingo | bingos |
| bronco | broncos |
| casino | casinos |
| cello | cellos |
| combo | combos |
| commando | commandos |
| condo | condos |
| disco | discos |
| duo | duos |
| dynamo | dynamos |
| embryo | embryos |
| espresso | espressos |
| fiasco | fiascos |
| flamenco | flamencos |
| gazebo | gazebos |
| ghetto | ghettos |
| hippo | hippos |
| igloo | igloos |
| inferno | infernos |
| kangaroo | kangaroos |
| kilo | kilos |
| kimono | kimonos |
| logo | logos |
| memo | memos |
| metro | metros |
| nacho | nachos |
| patio | patios |
| photo | photos |
| piano | pianos |
| placebo | placebos |
| pimento | pimentos |
| polo | polos |
| portfolio | portfolios |
| pro | pros |
| psycho | psychos |
| radio | radios |
| ratio | ratios |
| rhino | rhinos |
| salvo | salvos |
| scenario | scenarios |
| shampoo | shampoos |
| silo | silos |
| solo | solos |
| sombrero | sombreros |
| soprano | sopranos |
| stereo | stereos |
| studio | studios |
| taco | tacos |
| tango | tangos |
| tattoo | tattoos |
| tempo | tempos |
| trio | trios |
| tyro | tyros |
| video | videos |
| zero | zeros |
| zoo | zoos |
