This verb comes from the Latin words “dulcinficare” (“to sweeten”) and “dulcis” (“sweet”). The same root is used to indicate sweetness of all kinds — from dulcet tones to dulce de leche. To “dulcify” something implies sweetening its taste, but used in context with a person, the word describes soothing or calming them down. You can dulcify an upset friend, but you can also dulcify the coffee you drink while chatting with them.