Plain English Meaning
Working out when you are exactly over an intersection on a chart by checking that two navigation signals line up at the same moment, showing you are sitting on the spot where they cross.
Full Definition
The procedure of confirming an aircraft's position over a published intersection — a fix defined by the crossing of two or more navigation courses, such as VOR radials, bearings, or airway centerlines — by tuning, identifying, and centering the appropriate navigation signals so that each course indicator confirms the aircraft is on the defining radials or bearings simultaneously.