noun

• (figurative) Something that is very strong but also very rigid.
  "A new skiercross pro tour is on the docket, as well as freeskiing. Just like racing, both require strong but supple legs rather than jackhammer quads."

verb

• (intransitive) To use a jackhammer.
  "Early the next day a crew came to fix the street. Vernon was out there at once, watching them jackhammer and haul the asphalt […]"
• (transitive) To break (something) using a jackhammer.
  "The foundations for the barrier had been jackhammered away; the piles of broken concrete were just left alongside the road."
• (transitive) To form (something) using a jackhammer.
  "Small ledges had been jackhammered at each end of the crater and timbers bolted into them, forming abutments of the bridge that was to come."
• (intransitive, figurative) To move like a jackhammer.
  "[…] a bolt of lightning jackhammered across the sky, interrupting his dream."