The concept of "behavior" is central to the activities of the Animal Behavior Society and its members, but do we know what we mean by this term? Most published sources either do not include a definition of the word "behavior", or have definitions that both contradict each other or are either too broad or too narrow to be applied operationally.
We examined the range of available definitions, and finding no consensus, polled members of ABS as to their understanding of the term. Here again, we found surprisingly widespread disagreement as to what qualifies as behavior. This paper highlights the areas of agreement and disagreement, and proposes a definition intended to be operational and as free as possible of taxonomic bias.