Search Result for "abney level":
Wordnet 3.0

NOUN (1)

1. a surveying instrument consisting of a spirit level and a sighting tube; used to measure the angle of inclination of a line from the observer to the target; 



WordNet (r) 3.0 (2006):

Abney level
    n 1: a surveying instrument consisting of a spirit level and a
         sighting tube; used to measure the angle of inclination of
         a line from the observer to the target