A definition is "a statement conveying fundamental character;" if something fulfills a definition of a thing, this fulfillment is what causes it to be categorized as that thing; to define something is to give a definition for the thing concerned.
painful to come up with for people who hate themselves, and lack the imagination to connect with any form of reality or meaning and are actually running away from making any sense of what has and is happening around them and chose to be mostly oblivious to what they are experiencing.
friend: "what is the definition of the word relapse?"
friend: "is it almost like you tried to stop watching movies for once and then went back into the habit of devouring them?"
me: "dude, I don't care about you trying to figure out what relapsing is, go away"