Lateral Rigidity – the structural integrity of footwear for lateral movement, offering enough stiffness to prevent ankle damage on long hikes
 
Longitudinal Rigidity – the lengthwise structural integrity of a piece of footwear, extra stiffness provides additional support when pressure is exerted on the heel and toe areas  
 
Magnetic Declination – the angle between the actual North Pole and the magnetic north
 
Midsize Packs – a backpack designed to carry an amount between the “Day Pack” and the “Expedition Pack”

 
Mountaineering – hiking through mountains; often requires rock or ice climbing and other skills
 
Mountaineering Boots – heavy-duty hiking boots often either equipped with “Crampons” or capable of having them attached.