omega 

(noun) 
[oe·MEG·ah, oe·MEE·gah, oe·MAY·gah] 


1. the 24th and final letter of the Greek alphabet 

2. the end, or the last in a series or sequence: "Alexis may know more about business than you do, but she isn't the alpha and omega on the subject, as she would have you believe." 


Origin:

Approximately 1400; from Middle English; borrowed from Greek, 'omega': large o (so called because it was a long vowel in ancient Greek), ('o': the letter o + 'mega,' neuter of 'megas': large, great, which is related to the root 'meg-': great). 

In action 

"It's hard to imagine that two slim books, both designed for the smallest room of the house (the one with the most plumbing), could explain all there is to know about the ever-fraught and complex subject of dating. Nevertheless, these two, 'A Very Lonely Planet' by Ryan Bigge and 'My 1,000 Americans' by Rochelle Morton, do. Nothing more should be written on the topic, and all the umpty-hundreds of volumes that've already appeared should be tumbled from the shelves and set on fire. Bigge's book and Morton's -- a boy book and a girl book -- together constitute a virtual alpha and omega of American courtship, circa 2001. And once you've read them, you'll never go out with a member of the opposite sex again, for fear of looking into their eyes and seeing a Bigge or a Morton reflected back at you."

Gavin McNett. "Single, with complexes: A pathetic guy and a fraudulent girl offer books about the dating life that will make you happy to stay home." Salon.com (August 28, 2001).

"I am Alpha and Omega, the beginning and the end, the first and the last."

Revelation [last book of the] New Testament (c.A.D. 95).