A small portion or serving (a reduced amount compared to the regular portion), often used when ordering food.
ラーメンは小盛りでお願いします。多すぎると食べきれないので。
I'll have the ramen in a small portion, please. I can't finish too much.
定食のご飯を小盛りにすると、少し値段が安くなる店もある。
Some places reduce the price slightly if you choose a small portion of rice with a set meal.
健康のために昼は小盛りにしている。
I keep my lunch as a small portion for health reasons.