"Military and Police".
For older S&Ws, it refers to the revolver that eventually became the Model 10. It was introduced in 1899 as the "Military and Police Hand Ejector" model. Right now, it seems to be a tag for products that are presumably aimed at the same. The M&P340 and 360 are different from the regular models.
"Model: 360PD
Caliber: .357MAG/.38+P
Capacity: 5 Rounds
Barrel Length: 1 7/8"
Front Sight: Red Ramp Front
Rear Sight: Fixed
Grip: Rubber Grips
Frame: Small - Chiefs Special Style
Finish: Blue / Black
Overall Length: 6 3/8"
Material: Scandium Alloy/Titanium/Stainless Steel
Weight Empty: 12 oz. "
"Model: M&P360
Caliber: .357MAG/.38+P
Capacity: 5 Rounds
Barrel Length: 1.87"
Front Sight: XS Sights® 24/7 Tritium Night
Rear Sight: Integral U-Notch
Grip: Synthetic
Overall Length: 6.31"
Weight Empty: 13.3 oz.
Material: Scandium Alloy Frame/Stainless Steel Cylinder
Finish: Matte Black
Frame Size: Small - Chiefs Special Style
Action: Single/Double Action"