divot

1. (especially golf) A torn-up piece of turf, especially by a golf club in making a stroke or by a horse's hoof.Examples: "Usually her voice came over the wire as something fresh and cool, as if a divot from a green golf-links had come sailing in at the office window, but this morning it seemed harsh and dry."; "Soon, thick dark tufts of hair began to spread across his scalp, hanging over his ears, a moor of unruly divots which he was first unable to tame and with time willingly cultivated."especially

2. (mathematics, astronomy) A drop in a graph between two linear portions (example)