Evolution synonymous with adaptation [rant]

[Jet Black]

why on earth do so many scienctific sources treat the word adaptation as synonymous with evolution? It's most irritating. We already have a word for changing allele frequencies as a result of differential reproductive success; evolution, and adaptation also has the meaning of "non-inherited structural or behavioural changes of an organism in response to it's environment". I find this most annoying and will no doubt continue to do so until either I change the mind of the scientific community, or someone justifies to me why adaptation is also appropriate in a genetic and evolutionary context when we already have the word evolution which does the job. It makes life rather difficult when dealing with creationists for one thing.

thankyou for reading my rant, if someone could do something to calm me down that would be excellent.