What is Absolute Pin?
Chess Terms : Absolute Pin Explained
Absolute Pin
An absolute pin is a pin in which the pinned piece shields the king. Since moving the pinned piece would expose the king to check—which is illegal—the pinned piece cannot move at all. An absolute pin is therefore a complete immobilisation of the pinned piece. Contrast with relative pin. 
The black knight on d7 is absolutely pinned by the white bishop on f5—moving the knight would expose the black king to check.Board is interactive - move a piece