What is the meaning of the term “thread-safe”?

Question

Does it mean that two threads can\'t change the underlying data simultaneously? Or does it mean that the given code segment will run with predictable results when multiple t

Answer 1

In simplest words :P If it is safe to execute multiple threads on a block of code it is thread safe*

*conditions apply

Conditions are mentioned by other answeres like 1. The result should be same if you execute one thread or multiple threads over it etc.