The Collaborative International Dictionary
Afoul \A*foul"\, adv. & a. [Pref. a- + foul.]
In collision; entangled.
--Totten.
To run afoul of, to run against or come into collision with, especially so as to become entangled or to cause injury.
Usage examples of "to run afoul of".
To a man, they wore the red badges of Amefel, having no wish to run afoul of their own watchers in the hills.
She stepped carefully, so as not to run afoul of the hobble and trip and fall.
He was lost and certain to run afoul of the war as it was breaking out.
Unless he was willing to run afoul of whatever was responsible, he would have to stay mundane himself.
This cold and unrewarding duty made a convenient punishment for any guard who chanced to run afoul of the moody Baron's whims, and so was usually the lot of the younger and more cheerful among the company, as the Baron was prone to consider it a mortal offense should anyone be happy when he himself was sunk in one of his frequent and incapacitating fits of black depression.
It could not afford to run afoul of the neighbors without causing long-range strains in which it had the most to lose.
Even though he wasn't a vampire, it occurred to her that he would be a very dangerous man to run afoul of.