n.  1.  The name of the Greek letter  
2.  (Anat.) The point of junction of the sagittal and lambdoid sutures of the skull.  
3.  (Phys.) A subatomic particle carrying no charge, having a mass equal to 2183 times that of an electron; it decays rapidly, typically forming a nucleon and a pion.

Noun  1.  lambda  the 11th letter of the Greek alphabet 
2.  lambda  the craniometric point at the junction of the sagittal and lamboid sutures of the skull 
LAMBDA  A version of typed lambdacalculus, used to describe
semantic domains. ["Outline of a Mathematical Theory of Computation", D.S. Scott, TM PRG2, PRG, Oxford U, 1971]. 