'Rugged' has a few meanings: 1: having long narrow shallow depressions (as grooves or wrinkles) in the surface; 2: sturdy and strong in constitution or construction; enduring; 3: very difficult;...
Mean can mean you are being rude or in math terms it is adding a set of numbers then dividing by the total amount. ex. If your numbers are 1,2,and 3 add them to get 6 and divide by 3. You get 2.