Though, based on the amount of data Google has on the average user, and the fact that you have to sign-up to get an API key which is presumably associated with your search history, Gmail history (either any conversations sent from your Gmail account, or any mail you received dispatched from a Gmail account directed at you), they could easily determine if you meant Apple the fruit [you work for the USDA], Apple the company [you're an engineer in SF with a User-Agent history that's very heavily skewed towards Safari], or etymological basis of Apple, the word [you're a linguist], and disambiguate based on aggregate information. I'd imagine it'd be pretty trivial to do with their existing advertising profile + visit history of any site that either has Google Analytics or a Doubleclick ad.
[1] Again, I struggle to call it a graph, even if it's implemented as a GDB on Google's end, until the end-user traverses it, it's just a Knowledge API.
[2] https://developers.google.com/knowledge-graph/reference/rest... See: `types'.