The definition of quality is complex, elusive, and ambiguous. Cross-disciplinary definitions, usually assumed to be identical, vary in significant and subtle ways. Clear definition of a problem is the first step in correcting or improving it. Therefore, identification and increased understanding of disciplinary definitions of quality healthcare are needed. Development of a universal definition would be the ideal solution and would support quality improvement and patient safety efforts and programs. This article compares and contrasts definitions of quality in four selected healthcare disciplines and offers recommendations for how healthcare quality professionals might address and mitigate the ambiguity.