The familiar and ubiquitous phenomenon of ion-cyclotron damping is shown to be invertible in a laboratory plasma resembling ionospheric plasma in terms of important dimensionless parameters. The ion-cyclotron waves that arise spontaneously appear at all harmonics of the ion-cyclotron frequency, well into the lower-hybrid range. The sign change of the usual ion-cyclotron damping is induced by shear in the magnetic-field-aligned (parallel) ion drift velocity. Full experimental characterization of the wave propagation and particle-velocity distributions are presented to document the case of inverse damping (i.e., growth) and the case in which the damping is significantly reduced. These results support the parallel-velocity-shear interpretation of the multiscale structure observed by the Fast Auroral Snapshot (FAST) satellite. FAST observations of simultaneous shear and multiharmonic ion-cyclotron waves in the upward-current and downward-current regions of the ionosphere (4000-km altitude) are presented and discussed in terms of a new, small-scale analysis of the mechanisms in the auroral region.