There is a helpful rule to form the plurals of words ending with o, but there are many words that are rule-breakers!
Follow this guideline for many words:
If it's a music word, simply add s. Examples: piano, pianos cello, cellos alto, altos
If it's not a music word, check the letter in front of the o. If it's a consonant, add -es.
If it's a vowel, add s.
Examples: hero, heroes potato, potatoes hobo, hoboes
rodeo, rodeos Oreo, Oreos
Lots of words break the rule however, and some go either way.
photo, photos
hello, hellos
auto, autos
pimento, pimentos
zero, zeros or zeroes
buffalo, buffaloes, buffalos, or even buffalo
Some Scrabble words that end with O are:banjocockatoocombocommandocuriododominodumbodynamoechogizmogogoohalohelloherokangarookazookiddokilokimonomemonopatiopeekaboopotatoradiorodeosotattoototomatotootornadotorsotriovetovideovirtuosowhowooyahoozerozoo
Some words ending in the vowel O are:bongobravohalohelloherojellopianopolopotatoshampoosilosolotattootomatoweirdozero
Some 5 letter words that end in O are:bingobongocuriocellocondoCongodingodiscodittofoliohellojellolassolingopatiopintopromopolioradioratiorodeoromeostenovireoVirgo
tornadotorpedo
Some four letter words that end with "o" are:zerohaloherohobointojudokiloalsoaltoautoechomemoontopolosilosolotacotarotrioundoveto
Because there is no standard rule for words ending in -o.
Some plural words ending in "o" are photos, pianos, casinos, and zoos.
Some words ending in o that form their plural by adding s only include: pianos, duos, solos, tacos.
The general rule for forming the plural of nouns ending in -o is to add -s (e.g., piano - pianos). However, if the noun ends in -o preceded by a vowel, you would add -s (e.g., zoo - zoos) or -es (e.g., potato - potatoes) to form the plural.
Nouns that end in 'o' in their singular form can take an 's' or an 'es' for their plural form. Some examples:echo to echoeshero to heroespotato to potatoesveto to vetoesauto to autosphoto to photosstudio to studiospiano to pianos
It says in the rule of forming singular noun to plural add "S" to nouns ending in "O" preceeded by a vowel .
Nouns ending with -o that form the plural by adding -s to the end of the word are:autoscameoskangarooskilosmemosphotospianossolosstudiostattoosvideoszoos
There is no hard-and-fast rule with regard to forming the plural forms of nouns ending in O. Some nouns adopt the ending -es, such as heroes, tomatoes, potatoes. Other nouns (especially those with two ending vowels) simply adopt an S, such as cameos, patios. Others appear in both forms: zeros/zeros, volcano/volcanoes, tornados/tornadoes. (The -es in these three is the dominant usage.)
The general rule in English usage is that if the noun ends in a vowel followed by o you add an s; if it ends in a consonant followed by o you add es. There are, however, a number of exceptions to the latter rule: pianos, solos, photos, memos, etc.]
The plural form photos is an exception to the rule that words which end with -o preceeded by a consonant have -es added to create the plural form.
In Spanish, most nouns ending in "o" are masculine and singular, while most nouns ending in "os" are masculine and plural. For example, "libro" (book) is singular and "libros" (books) is plural. Keep in mind that there are exceptions to this rule, so it's always best to check the gender and number of each noun individually.
There's not a good one. You just have to memorize the "oddball" words that take "es" as an ending. Most words ending in "o" will just take an "s" as the ending. Use a Study Deck - see the link - to memorize the other words. Here's another good link to show you some of the most common plural endings for "o" words, too.