Defining what is meant by 'life' seems, on the face of it, straightforward. But, as this article explores, once you delve below the surface you find that providing a definition that everyone agrees upon is nearly impossible. By first considering how biologists and philosophers of science debate the issue of defining life, the article then goes onto explore the implications of this for the biology classroom. Finally, the debate is widened to include the 'meaning of life', suggesting that a cross-curricular approach to addressing questions of this type is a powerful approach for students to work with.