Look up: pH Level

1. 
   pH Level
   Measurement that tells a scrapbooker how acidic or basic something is. For scrapbooking, you want to use products with a pH level of 7 or above.
   Found on http://www.scrapdirectory.co.uk/scrapboo
   
   
2. 
   Physical activity level
   The `Physical activity level` is a way to express your daily physical activity in a number. This number is defined as a multiple of your Basal metabolic rate, which is the amount of energy you consume while inactive (for example, while you sleep). The `Physical activity level` decreases with age. It can be used to compute the amount of energy one needs to eat in combination with the Basal metabolic rate computed from for example Basal metabolic r...
   Found on http://en.wikipedia.org/wiki/Physical_ac
   
   
3. 
   physical level
   (from the article `computer science`) ...and hence of their implementations. Each layer is defined by the functions it relies upon from the next lower level and by the services it ... ...acknowledgment frames sent back to the source by the destination. This layer also establishes frame boundaries and implements recovery procedures ... ...
   Found on http://www.britannica.com/eb/a-z/p/62