“When you use the word ‘accident,’ it’s like, ‘God made it happen,’ ” Mark Rosekind, the head of the National Highway Traffic Safety Administration, said at a driver safety conference this month at the Harvard School of Public Health. “In our society,” he added, “language can be everything.” Almost all crashes stem from driver behavior like drinking, distracted driving and other risky activity. About 6 percent are caused by vehicle malfunctions, weather and other factors. Preliminary estimates by the nonprofit National Safety Council show deadly crashes rose by nearly 8 percent in 2015 over the previous year, killing about 38,000 people.