autoRotation property

For horizontal axes, the allowed degrees of label rotation to prevent overlapping labels. If there is enough space, labels are not rotated. As the chart gets narrower, it will start rotating the labels -45 degrees, then remove every second label and try again with rotations 0 and -45 etc. Set it to undefined to disable rotation, which will cause the labels to word-wrap if possible. Defaults to [-45]`` on bottom and top axes, undefined` on left and right axes.

API Docs: https://api.highcharts.com/highcharts/chart.parallelAxes.labels.autoRotation