Translation guide
Japanese words for 'detergent' depend on what you are cleaning: laundry, dishes, or general household surfaces. The most common everyday word is 洗剤 (せんざい), but specific types have their own names.
A substance used for cleaning, especially laundry or dishes.
The most common and general word for detergent. It covers laundry detergent, dishwashing liquid, and other cleaning agents.
I need to buy detergent.
This detergent lathers well.
Detergent specifically for washing clothes.
Detergent for washing dishes by hand or in a dishwasher.
Detergent in powder form, often for laundry.
Powdered detergent. Common for laundry.
Powdered detergent is cheaper than liquid.
Detergent in liquid form.
Liquid detergent, used for laundry or dishes.
Liquid detergent dissolves more easily.
In daily conversation, 洗剤 (せんざい) is often enough. Context usually makes it clear whether you mean laundry or dish detergent. If you need to be specific, add 洗濯 (せんたく) or 食器 (しょっき).
石鹸 means 'soap', not detergent. While some cleaning products are soap-based, 洗剤 is the correct word for modern synthetic detergents.
I need to buy more dishwasher detergent.