Noun
Any apparently useless activity which, by allowing one to overcome intermediate difficulties, allows one to solve a larger problem.
I was doing a bit of yak shaving this morning, and it looks like it might have paid off.
A less useful activity done consciously or subconsciously to procrastinate about a larger but more useful task.
I looked at a reference manual for my car just to answer one question, but I spent the whole afternoon with my nose buried in it, just yak shaving, and got no work done on the car itself.