Im*pact" (?), v. t. [imp. & p. p. Impacted; p. pr. & vb. n. Impacting.] [L. impactus, p. p. of impingere to push, strike against. See Impinge.] To drive close; to press firmly together: to wedge into a place. Woodward.

Im"pact (?), n. 1. Contact or impression by touch; collision; forcible contact; force communicated.

The quarrel, by that impact driven.

2. (Mech.) The single instantaneous stroke of a body in motion against another either in motion or at rest.

• a significant or strong influence
       His friend's opinon had an impact on his decision.
       Which concrete we use will have a tremendous impact on the building's statics.
  
• (the force or energy of a) collision of two objects
       The hatchet cut the wood on impact.
  
• (mainly medical) a forced impinging
       His spine had an impingement; L4 and L5 made impact, which caused numbness in his leg.
  
• to influence; to have an impact on
       I can make the changes, but it will impact the schedule.
       
• Usage note: Some authorities object to the use of impact to mean "to influence; to have an impact on". However, such usage has a long history, and appears to be becoming increasingly acceptable.
  
• to collide or strike
       When the hammer impacts the nail, it bends.
  
  French
• impact