1. a device that allows equipment to be connected or used in a way different from its original design
2. a person who adapts something, especially a literary work for a different medium

Examples

• I need a power adapter to charge my laptop in Europe.
• The USB adapter allows me to connect my old printer to the new computer.
• She plugged the headphone adapter into her phone.
• The travel adapter works in multiple countries.
• The screenwriter was the adapter of the novel for the movie.
• He used an HDMI adapter to connect his tablet to the TV.
• The adapter converted the signal from analog to digital.