The earliest Google hit I could find for "twangitude" was in an archived chat from 1998. A portmanteau of twang and "attitude," the intervening years haven't exactly pushed the word to the top of the charts, but a few fans, critics, and even composers of country music have found it clever enough to repeat, including a 2012 song by Donna Devine, who rhymed it with "bangitude."
The word embraces three meanings of "twang":
a. A particular guitar sound.
b. A nasal vocal style used by some male country singers — think Willie Nelson — that enables reaching higher notes without falsetto.
c. A regional accent heard from southern Ohio through the Mountain South to Texas affected or retained naturally by the vast majority of country singers — except for Garth Brooks, who was born in Tulsa, which lies outside of twang country.
The meaning would thus be the style, affect, and sound of country music and its performers. Sequins and fringe are likely obligatory.