1. The step siblings I acquired in adulthood.
    Step-sibling seems too intimate when we didn't grow up together. "In law" would be closer, but confusing. There should be a generic "closely related to someone I'm closely related to" word.
  2. Depression.
    The disease. Not to be used interchangeably with "sad" or "unhappy" or to mean grief stricken or devastated. I wish there was a word that meant, clearly and distinctly: "Depression, the medical and chemical issue that needs to be treated because it's serious and life threatening."
  3. Forgetting what you walked into the room for.
  4. Binge watching a TV show.
    I just don't like "binge." Say it three times fast. Yuck, right?
  5. Overmorrow
    It means "the day after tomorrow" but no one uses it.
  6. Boyfriend/Girlfriend
    After four or five years of dating there should be an upgraded term.
  7. The joy of someone else doing a small task for you.
    Making you a sandwich, picking up something you dropped, holding the door. They didn't have to, there's no expectation of repayment, they're just making being a human a little easier for a moment.