A neuron is a specialized cell which transmits nerve impulses.  We have them in oiur brains.  The word has ancient origins: the Greek word "neuron" meant sinew or tendon.  As a prefix, neuron crops up a lot: neuroscience, neurochemistry, neuropsychology, and onto neurosis and neurotic. 

Get ready for the next bit - it will blow your mind!  Take a deep breath -

we have a hundred billion neurons in the brain; infants create as many as 1.8 million neural connections per second; sixty (yes, sixty!) neurons are capable of making ten to the power of eighty one possible connections, which is a number ten times as large as the number of particles in the observable universe!

And while we are on the subject of the brain: simply the ability to distinguish between the sounds of "P" and "B" involves as many as twenty-two sites across the brain.