Inconsiderate behavior is rude: it doesn't take into consideration the feelings of other people.
When you're considerate, you're polite and thoughtful. You consider other people's feelings. When you add the prefix -in (not) to considerate, you get its opposite. Not writing a thank-you note for a gift is inconsiderate. Not returning a phone call is inconsiderate. Not inviting a friend to a party is inconsiderate. Most inconsiderate behavior is also selfish.
