Etymological information is an expected type of information in historical dictionaries, but it also appears in many general dictionaries, while it is the key information in etymological dictionaries. Etymologies are generally considered to trace the history of words. However, the notion of a word in this statement is an abstraction in more than one way. First, the questions of which forms and which meanings should be placed together as a word does not have an obvious answer. Moreover, the question of which words there are in a language at a particular time cannot be answered on a purely empirical basis. In the light of such observations, I show that what is recorded in an etymology can best be interpreted as the history of the motivation speakers had for the combination of a particular form with a particular meaning. This does not subtract from the value of etymological information, but gives a linguistically sound interpretation of what etymologists have tried to achieve.