Undiluted means not weakened, reduced, or mixed with anything else. When something is undiluted, you're getting it at full strength, in its pure, original form.

You might dilute lemonade by adding water to make it less sweet and sour. But undiluted lemonade is the concentrated version: intensely sweet and powerfully tart. Some medicines come as concentrates that need to be mixed with water or juice, but if you accidentally drink the undiluted version, you'll taste how strong it really is.

The word also describes experiences or emotions at full intensity. Undiluted joy means pure happiness without any sadness mixed in. Undiluted truth means the complete, unvarnished facts without anything softened or left out. When a teacher gives you undiluted praise, they're not adding any “but you could improve this” remarks.

The opposite is diluted, which means weakened or watered down. Think of how a small drop of food coloring in water creates a pale tint, but the same drop undiluted is a rich, intense color. Undiluted means experiencing something in its strongest, most concentrated, most genuine form.