Library/information science professionals need a clearly articulated definition of usability/Web usability to implement intuitive websites. In this study, the authors analyzed usability definitions provided by the ARL library professionals and those found in the library/information science and computer science-information systems literature. Quantitative and qualitative methods were used to identify similarities and differences between the attributes emphasized by the two sets of definitions based on information behavior models and human-computer interaction (HCI) frameworks. Results indicated that both groups overlooked critical usability elements, such as environment and information objects/content/resources. Thus, the authors proposed a working, multi-faceted definition that presents a holistic view of usability. (Contains 53 notes, 6 tables and 7 figures.)