"Placing an essential oil directly on the skin or other surface of the body.
"Topical application is the process of placing an essential oil on the skin, hair, mouth, teeth, nails, or mucous membranes of the body. Applying essential oils directly on the body without dilution is commonly referred to as applying the oil “neat”. Since essential oils are so potent, and because some essential oils may irritate the skin or other areas of the body, they are often diluted with a pure vegetable oil (usually called a “carrier oil“) such as fractionated coconut oil, almond oil, olive oil, jojoba oil, etc." –Modern Essentials®
Some of the most common ways to enjoy topical application are by direct application, massage, reflexology/reflex therapy, auricular therapy, compresses, and baths.