What's a single word for the context a word is used in (used to differentiate similar words)?
I saw a question on this site asking about the difference between two similar words and one of the answers said it was the specific context each word was used in, except they used a single word that meant that.
I think you may be referring to contextualization:
To contextualize:
to place (a word or idea, for example) in a particular context.
to put (a linguistic element, an action, etc.) in a context, esp. one that is characteristic or appropriate, as for purposes of study.
Source: http://www.thefreedictionary.com