In version 10.1 ContourIntegral seems to be a keyword as it appears in the completion box. However, one cannot access to the documentation page by pressing “F1”.
Does anyone know what is it for?
Somewhat related Q&A: (17429), (39987), (74089)
– Michael E2
Feb 7 at 16:53
It’s an undefined symbol, which the user may define. It also has its own input form.
\[ContourIntegral] f \[DifferentialD]x // FullForm
See also the tutorial Operators without Built-in Meanings.