Potato (the tuber); the loanword often used in culinary contexts or product names.
ポテトを皮ごとオーブンで焼いてみたら、とてもおいしかった。
I tried roasting potatoes in the oven with the skins on and they were very tasty.
この店のポテトサラダは評判がいい。
This shop's potato salad has a good reputation.
市場で新鮮なポテトが安く売っていた。
Fresh potatoes were being sold cheaply at the market.
Colloquial abbreviation for french fries (fried potato); commonly used on menus and in conversation.
セットのポテトはS、M、Lから選べます。
You can choose S, M, or L for the fries in the set.
子どもたちはケチャップでポテトを食べるのが好きだ。
Kids like to eat fries with ketchup.
ハンバーガーにポテトが付いているので昼食はそれにしよう。
Since the burger comes with fries, I'll have that for lunch.
Sometimes used as an abbreviation to mean sweet potato (satsumaimo) in colloquial contexts; context determines meaning.
このスイーツはポテトを使ったタルトだが、さつまいもがベースになっている。
This dessert is a potato tart, but it's based on sweet potato.