Words stand not only in relation to the world but also to human mind. So in addition to reference, there is another dimension of word meaning called sense. For example, when you hear the expression dog, you will naturally reflect on its features in addition to the kind of animal as the referent of the expression. Sense is mental representation, the association with something in the speaker/hearer's mind. Words like dragon, but, of and phrases like a round triangle have sense, but no referent. Words like dog, horse, car and gun have both referent and sense. The study of meaning from the perspective of sense is called the representational approach. The following sections will explore how to analyze meaning along this line.