Etymological definition: To note or perceive differences between things. (Strictly speaking "discrimination" makes no mention of race, gender, nor disability; nor does it make mention of placing one thing at a disadvantage to another.)
White Unicorn definition: Any policy that treats people equally regardless of race, gender, or disability.
Real world definition: Any policy that doesn't place white males at an extreme unfair disadvantage.
Equivalently, any policy that doesn't specifically mention race and gender in the context of "protected minorities receive X benefits", where X is greater than those received by white males.
In the real world, any policy based strictly on academic merit, financial status, or any other non-race based trait, even those claimed by tolerance experts to not be correlated to race, is discriminatory unless it specifically allots a handicap to women and non-whites.
Dictionary nerds: The act of selecting toothpaste based on each item's price and advertised benefits is an example of discrimination.
What the media wants you to think: A bunch of people of all races and genders holding hands around a 1000 year old tree is the ideal discrimination-free environment.
What's really happening: Michigan placed a ban on using race and gender as a factor in college admissions. While this seems like the ultimate move in preventing discrimination, as it would be impossible to discriminate based on race or gender if these factors were absent in a college application, the measure was struck down by a federal court.
They claimed the policy harms minorities and is unconstitutional; as it would then also be impossible to give PREFERENTIAL treatment to minorities as well.
The more you know.