Meaning

noun a tool with a sharp point and cutting edges for making holes in hard materials (usually rotating rapidly or by repeated blows)

noun similar to the mandrill but smaller and less brightly colored

noun systematic training by multiple repetitions

originUncertain. Compare the same sense of trill, and German trillen, drillen. Attestation predates Etymology 1.

Etymology from Wiktionary, CC BY-SA 3.0