1. Nervous and on edge.
2. A guitar tuning where the E, A, and D strings are replaced by lighter strings and tuned an octave higher than normal. The G, B, and E strings are used regular string gauges and are tuned as normal. High-strung tuning is used for several African folk music styles.
The advantages of high-strung tuning over the very-similar Nashville tuning are that the G string uses a regular string gauge and tuning, thus it is easier to play and lasts longer.
However, high strung doesn’t provide the same octave-displaced G string, so it sounds different from Nashville tuning — it can’t be used to double a regular guitar for a true 12-string guitar effect, and overall, has a less “chiming” and “mandolin-like” sound.