1. To place or rest someone or something inside of something. In this usage, a noun or pronoun is used between "set" and "in." You can set your tools in that box by the door on your way out. He set the sleeping boy in his bed.

2. To become or begin to be established, especially something potentially unpleasant, undesirable, or harmful. As the heatwave sets in across the state, people in some areas are being advised not to leave the house. This part of town always gets a bit spooky when darkness sets in. The trick to cleaning a stain is to start on it right away. Never give it enough time to set in.

3. To attach or affix; to insert. I had my tailor set in a wool lining so that my jacket would be warm enough for the winter. You have to set in the mounting brackets with a screwdriver first before you can hang your television.

4. To become established in one's mind; for something to be understood or accepted. Once the realization of what she'd done set in, I called the police immediately. It took a moment to set in that I wouldn't be returning to this house ever again.

5. To establish some time or place as the setting of a story, play, or film. In this usage, a noun or pronoun can be used between "set" and "in." The novel was originally set in China, but they changed it to Japan for the film. I'm not sure why they set the sequel in the past.

6. To set typewritten writing in a particular font or style. I've set the main points in bold so your eye will be drawn to them during your speech. Make sure your essays are set in Times New Roman.