Why does tomato end with oes for plural?

Answer 1

The plural of tomato is tomatoes, ending in oes, and like most spelling rules, the reason it's done is because that's the way it's always been done.

There are a few guidelines for when to add ES to words that end in O, but the simplest way to handle the problem is just to memorize a list of common words that do it:

buffalo buffaloes

domino dominoes

echo echoes

embargo embargoes

hero heroes

mosquito mosquitoes

potato potatoes

tomato tomatoes

torpedo torpedoes

veto vetoes

Otherwise you can usually just add an S.

Answer 2

The plural form of "tomato" is "tomatoes" because most English nouns form the plural by adding -s or -es to the end. In this case, the -es is added because the word ends in a consonant followed by an -o. This is a general rule in English grammar for forming plurals.