Crosscutting concepts, such as "structure" and "function," are present in courses at multiple educational levels across the disciplines. These two terms are used individually in everyday language and have a long, rich history. The authors explore the meaning and presentation of biological function, which often is not clearly defined. Yet the history, cultural significance, and uses of this term have potential impacts on student understanding. Relying on students' past experiences or the English language definitions of the term may create difficulty when students attempt to integrate scientific thoughts and ideas. The authors call upon educators to provide definitions that are relevant to the situation or course.