A spoon, a utensil used to scoop and carry liquids or powders to the mouth. Often used interchangeably with 'spoon' (commonly written in kana).
コーヒーに砂糖をさじ一杯入れる。
Put one spoonful of sugar in the coffee.
スープをさじでかき混ぜた。
He stirred the soup with a spoon.
小さなさじが見つからない。
I can't find the small spoon.