mox·ie (mks)
n. Slang
1. The ability to face difficulty with spirit and courage.
2. Aggressive energy; initiative: "His prose has moxie, though it rushes and stumbles from a pent-up surge" (Patricia Hampl).
3. Skill; know-how.
[From Moxie, trademark for a soft drink.]
The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

moxie [ˈmɒksɪ] n
US and Canadian slang courage, nerve, or vigour
[from the trademark Moxie, a soft drink]
Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003
.,,.

A word I have always been fond of; came across it first in the works of the great Damon Runyon as part of the lively NY slang in use among his guys and dolls.

buck 3 (bk)
n. Informal
1. A dollar.
2. An amount of money: working overtime to make an extra buck.
[Short for buckskin (from its use in trade).]

Not sure how authenticated that ~~ sound as if might be a bit of post hoc folk etymology to me. But FWIW, guess it will do till a better derivation happens by...



Cheers, Roy

~Michael~