In other words, it is important the other persons understand what we want them to understand, that they understand the intended meaning. More precisely, purposeful communication is the transmission of intended meaning to others. Implied is that the sender of the communication has clear knowledge and understanding of the meaning he wishes to convey, and that the receiver interprets the message in such a manner that he receives the intended meaning. Hence for effective communication the sender must determine the purpose of the communication and use words which have the same meaning for sender and receiver. The scientific study of meaning is called Semantics.
Labels are arbitrary.
Two people can then be arguing about a concept, referring to it by using the same word, arguing because this word means something different to each of them. Words vary considerably as regards their value for communication. They differ in their level of abstraction. The greater the level of abstraction, the less meaning do they have. Here words are labels for objects such as table or chair.