Definitions

1. noun

a person who uses or smokes cannabis or other drugs, especially in large quantities

“He was a tweaker and had been using marijuana for years.”

2. noun

a person who is skilled in a particular activity or craft

“The mechanic was a tweaker when it came to fine-tuning engines.”

3. verb

to adjust or fine-tune something

“The engineer had to tweak the code to fix the error.”