The phrase "direct relation" means that two things are closely connected and affect each other directly, without anything else in between. Full definition
Good fats are a great source of calories and they are in direct relation with the testosterone (male hormone responsible for bigger muscle mass) in the body. (fitnessandpower.com)
Additionally, family members (direct relations like parents, children, siblings, and spouse) can also get coverage under a single plan, as specified in the policy. (policybazaar.com)
In fact, over the last few years, the mass market form of book continues to shrink in sales almost in direct relation to the growth in ebooks sales. (deanwesleysmith.com)