Moxie is bitter enough that the word has become synonymous with courage, as in "It takes moxie to do that!" (Upper case is unnecessary in this, a more generic, usage.)
Obviously, it's an Indian name... a look at the map of Maine showed me Lake Moxie, nestled up heading toward the Quebec border on the New Hampshire side. However, as it was related to me by someone from New Hampshire who lived in Maine for awhile and who loves the soft drink, the word actually is from a local Indian dialect and means "bitter" or "bitter water." Apparently the lake contains some harmless mineral salts concentration that renders the water quite bitter: talc,perhaps... in any event, the soft drink name derives from that fact, not just the lake name, according to Elizabeth.
I enjoyed my first taste of it in September of last year when I lucked onto large bottles of it in a supermarket in Waterbury, CT. while visiting a friend in Litchfield. It was love at first taste. The company that makes it is in headquartered in Doraville, Georgia, but I've looked for years and never found it anywhere hereabouts; I'd been itching to try it since forever. It's funny that I have returning far-New-Englanders bring me back some of that along with Ipswich brews and local potato chips. Fortunately for me, a Diet Moxie is also on the market (I have to minimize my sugar intake) which lacks none of the amazing bitterness of the original.
It's the best soft drink I've ever found, disregarding Athens, Georgia's own late, lamented cherry-ginger conoction, Budwine. If only someone would get the rights to resurrect that!....
Pop-Culturally, Ort. Carlton in Athens, Georgia.