What is Blink-Jumping?
Solution 1:
Blink-jumping is the term used to describe combining the jump (standard or enhanced with Athletics) with the Blink power.
You do it in the dream where the Outsider first gives Corvo his powers. In that dream, there are a few of the platforms that are out of reach of a normal blink; you have to trigger Blink, then jump, and release blink.
This gives you (a) a farther range than you have with Blink alone, and (b) the ability to move higher than you normally are able. As you increase your agility power, you are also able to jump further, and indeed to double-jump. Both of these predictably increase your mobility with Blink. With Blink 2 and Athletics 1, it is quite amazing the freedom that using these together effectively can give Corvo in terms of mobility.
In the linked question, note that the answerer says "I don't really see how better jumping can help someone playing a stealthy non-killing character...". I infer that this is the reason for the reference to Blink-jumping.