The aim of this paper is to show that humanlanguage is context-dependent in a veryspecific way. In order to support this thesis,a detailed comparison is made between the waysin which verbal expressions depend on thecontext of occurrence and evaluation and animalcommunication systems. The comparisonhighlights a series of analogies anddifferences between human language and thecommunication systems of other animals. Myproposal is to use the term `indexicality' toindicate the characteristic way of using thecontext in human language and to use the moregeneral phrase `context-dependence' for thecorresponding phenomenon in animalcommunication systems.