Terms of admittance (9)

I believe the answer is:

passwords

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'terms of admittance' is the definition.
The answer and definition can be both related to communication as well as being plural nouns.
Perhaps you can see an association between them that I can't see?

This is all the clue.

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(Other definitions for passwords that I've seen before include "Secret words for authentication" , "Secret letters" .)

I've seen this clue in The Globe and Mail.

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