jaunty means having an air of bright, energetic optimism. It suggests bounce, vigor, enthusiasm, a joy of living. He went along at a jaunty trot - with a spring in his step, full of bounce. She wore her hat at a jaunty angle - this is a little trickier but suggests, instead of the hat sitting sedately on her head at a predictable angle, it had a tilt that suggested a sense of fun, of energy. To truncate means to cut off, to cut short. Railway lines are truncated when they are cut off at a certain point. The phone call was truncate by an outage on the line. Hope that helps