1. Let's clarify the "definitions for the four of them" you mentioned. 2. Could you please specify what "four" refers to? For example, four mathematical definitions, physics concepts, variables, or other entities? 3. Giving the exact definitions or terms will help me explain each one step-by-step in a learner-friendly way. 4. Once you provide the terms or definitions, I will break them down, show examples, and explain their meanings clearly. Please provide the four definitions, and I will assist you!