All 16 words, sorted alphabetically. Group them into four categories of four.
The four category names, easiest to hardest. No words revealed yet.
Theme name plus one word from each category.
BALL, BONE, FRISBEE, and STICK are all classic objects that dogs are commonly trained or encouraged to fetch and bring back to their owners.
DROVE, HOST, LOAD, and SCORE are all words that can mean a great quantity or a large number of something.
BOOT (wheel clamp), POINTS (added to your license), TICKET (fine), and TOW (vehicle removal) are all potential consequences of committing a traffic violation.
BELL (Alexander Graham Bell, telephone), DIESEL (Rudolf Diesel, diesel engine), SINGER (Isaac Singer, sewing machine), and WATT (James Watt, steam engine improvements) are all inventors associated with the Industrial Revolution era.