Michael Bontaites, 20, entered guilty pleas to felony criminal threatening and a misdemeanor charge of conduct after an accident on Tuesday afternoon in Rockingham County Superior Court.
The plea happened at a hearing in which Bontaites was expected to challenge a search of his vehicle by police that led to his arrest.
Bontaites remains free on bail pending his sentencing hearing on March 23. Prosecutors say Bontaites exited his truck holding a knife after crashing into the woman's vehicle along the Route 28 traffic circle in Derry on June 13.
In court on Tuesday, Bontaites claimed he never intended to harm the woman while brandishing the weapon.
"I did have it, but I did not threaten her," he told Judge Marguerite Wageling.
She said, "Do you agree someone could perceive those acts as a threat even if your intent wasn't to convey that message?"
Bontaites agreed, and went on to plead guilty to the felony and misdemeanor charges.
Assistant County Attorney Lisa Cirulli said her office will ask Bontaites to serve at least half of a year-long county jail sentence when he is sentenced on March 23.
Bontaites would also receive an anger management evaluation upon his release and remain on probation for a year, according to terms of the agreement. He would receive a suspended year-long jail sentence for the conduct after an accident charge.
Public defender Emily Sieber will have a chance to argue for a lesser sentence at next month's hearing.
Had Bontaites gone forward with a trial, he could have faced up to 3½ to 7 years in state prison if convicted on the felony charges.
Prosecutors agreed to drop an operating after suspension charge as part of the negotiated agreement.