external
On or coming from the outside of something.
External means existing or happening on the outside of something, rather than the inside. When you paint the external walls of a house, you're painting the outside surfaces that face the street and yard. When a doctor examines someone for external injuries after a fall, they're looking at cuts and bruises visible on the skin, not internal problems like injuries to bones or organs.
The word often appears when we're making a distinction between what's outside versus what's inside. A computer's external hard drive sits outside the machine and connects with a cable, while an internal hard drive is built into the computer itself. External pressure comes from outside forces: a student might feel external pressure from parents to get good grades, separate from their own internal motivation to learn.
Scientists and engineers use external frequently when describing where forces or influences come from. An external force acts on an object from outside it, like wind pushing on a kite. External factors are conditions that affect something from outside: weather is an external factor that might cancel a baseball game, beyond the team's control.
The opposite is internal, meaning on or from the inside. Understanding this pair helps you describe precisely where something is located or where an influence originates.