In this paper, we present an architecture for software agents that enables them to learn vocabulary through the observation of each other bodies and actions. Besides sensors, effectors, and action control, the architecture provides the equivalent of a body with visual appearance. The agent soft visual appearance is designed to be seen by other software agents, not by people. The paper describes the agent software body with visual appearance, the learning mechanism, the demonstration scenario and presents some results showing that the agent software body allows agents to learn vocabulary through observation and to ground the meaning of the symbols they learn. The paper emphasizes the important role of social interaction in learning processes. Categories and Subject Descriptors I.2.6 [Artificial Intelligence]: Learning