Adding -s or -es to words ending in -o

Knowing when to add -s or -es to words ending in o is a bit tricky. But there are a few ways (rules!) to know which one to add. With some words, we can even have both endings.

a. If a word ends in a vowel a, e, i, o, u + O then we add -s: radio — radios, stereo — stereos, tattoo — tattoos. This is a good rule because we don't want 3 vowels in a row if we add -es!!! (studioes, zooes, tattooes x)

b. If a word ends in consonant + O then it gets tricky: kilo — kilos, zero — zeros, piano — pianos, photo — photos
but hero — heroes, potato — potatoes, echo — echoes, mosquito — mosquitoes, tomato — tomatoes. No rules for this but check below for possible ways to remember.

Some ways (rules!) to remember:
1. We add -s to some new words to English: photos, radios, stereos, videos, audios

2. We add -s to short forms/abbreviations: photographs — photos, kilos, autos, logos, typos, memos, egos, hippos, pros

3. We add -s to words from other languages, especially from Italian and Spanish: tacos, sombreros, stilettos, avocados, tornados, expressos, infernos, casinos.

4. We add -s to musical terms and instruments: pianos, solos, concertos, sopranos, cellos, altos, banjos

5. Remember we add -s to words ending in a vowel + o: tattoos, zoos, cuckoos, radios, studios, patios, ratios, scenarios, stereos, cameos.

We have some words ending in O that can be spelled with either -s or -es. Notice they all have a consonant + o.

cargo — cargos / cargoes

mango — mangos / mangoes

motto — mottos / mottoes

memento — mementos / mementoes

mosquito — mosquitos / mosquitoes

volcano — volcanos / volcanoes

buffalo — buffalos / buffaloes

tornado — tornados / tornadoes

flamingo — flamingos / flamingoes

fresco — frescos / frescoes

ghetto — ghettos / ghettoes

halo — halos / haloes

zero — zeros or zeroes ( some dictionaries allow -es spelling!!)

Some dictionaries have both spellings while some choose to stick to one spelling. Using online dictionaries is a great strategy. Look in the Oxford Dictionary or Cambridge Dictionary

Add -es to go and do to make these into third person verbs:  third person is he/she/it

      I go — she goes / he goes / it goes / does she?/ s/he/it doesn’t

      I do — he does / she does / it does / does it? /s/he/it doesn’t

Why?

If we didn't add e to goes it would be gos and sound like gos.  The e makes the 'o' a long sound.

Without the e in does, it makes dos.  But the 'e' doesn't make the o a long sound or it would be like the young deer does “doze”.

For more information about plural spelling rules click here for the 7 Plural Spelling Rules lesson.

For a more in-depth look at these rules then check out my Spelling Rules Course, or Spelling Rules Workbook

Do the exercise below.