COPULA

Couple: from the Latin copula "bond, chain; group of two persons bound by friendship, love".
 
“There was a time when men did not have the same shape as today. They were double beings who had both a female and a male sex. These beings were very strong and very proud: one day they decided to climb the sky in order to attack the Gods.

To punish them and weaken them, Zeus cut them in two. (...) Since then, each half has been searching for its complementary half”. 

Plato, The Banquet