1. To add to something existing
2. To add to the odometer
3. To apply to a surface: SYN. apply.
4. To perform
5. To put on the stove or ready for cooking

Pretended, assumed

1. An instance of putting someone on
2. Parody, spoof
3. Something done with the intention of fooling or deceiving people is a put-on.

When you place something on or apply something to your body, you put it on.
When you place something on or apply something to another surface, you put it on.
When you attach or affix something to another thing, you put it on.
When you put on weight, you gain weight.
When you organize or perform something for other people's entertainment, such as a play or a concert, you put it on.
When you put people on, you kid or tease them.