The word 业余 is formed by directly combining two conceptual building blocks: 业 (yè), which represents one's primary work, profession, or vocation, and 余 (yú), which means "surplus", "remaining", or "what is left over". The compound conceptually paints a picture of the time, space, or activity that exists outside of or left over from one's main professional domain, thus creating the meaning of "amateur", "spare time", or "extracurricular".