Words don’t have firm, unambiguous, unchanging meanings. This is a source of some frustration for me. The same word can have multiple meanings. Sometimes there are context-dependent meanings. Sometimes there are shades of meaning conveyed by tone of voice. People can have multiple interpretations of the same basic meaning of any given word. Clear communication is more challenging than it might appear to be.
In the field of software development, we have an unfortunate habit of re-using old words to represent new concepts. Maybe it’s because we value re-use (whatever that means). The English word, agile already had a meaning before software developers came along and started using it for something else. A ballerina is agile. A faun is agile. That’s easy to understand. Now, software development can be agile, too (whatever that means).