[Delphinaut]

Цитата из справки Delphi:

System.Classes.TThread.Terminate

Description

Signals the thread to terminate by setting the Terminated property to true.

Terminate sets the thread's Terminated property to true, signaling that the thread should be terminated as soon as possible.

For Terminate to work, the thread's Execute method and any methods that Execute calls should check Terminated periodically and exit when it's true.

Note: Unlike the Windows API TerminateThread MSDN, which forces the thread to terminate immediately, the Terminate method merely requests that the thread terminate. This allows the thread to perform any cleanup before it shuts down.