Definition of "head-on"

This secondary collision, head-on with a closing speed of 142mph, caused the DVT to veer off to the left. Many of the coaches behind it overturned and careered into an adjacent field.

2021 February 24, Greg Morse, “Great Heck: a tragic chain of events”, in RAIL, number 925, page 39

Wave direction and frequency (period) are two factors that influence the effect of waves on a moored ship. Whether the ship responds by surging, swaying or yawing will depend on whether the waves are striking the moored vessel head-on, beam-on or quartering, the frequency of the waves and the manner in which the tanker is moored.

2015, Duncan Bruce, Tanker Jetty Safety – Management of the Ship/Shore Interface (1st 2015 ed; second ed. January 2022)‎, 1st edition, Witherby Seamanship International, 3.1.2

During the day conditions worsened quickly—for example, a 2-6-0 on the Uckfield line suddenly encountered flood water high enough to enter its ashpan and extinguish its fire—until lock gates up-river at Barcombe gave way and a tidal wave rolled down the valley meeting head-on a spring tide rolling up from the coast.

1961 January, “Talking of Trains: Flooding at Lewes”, in Trains Illustrated, page 5

And there is little research to address the issue head on. A previous study, published in 2000, surveyed doctors and found that three quarters of them said some patients addressed them by their first name.

2022 October 13, Gina Kolata, “‘Kind of Awkward’: Doctors Find Themselves on a First-Name Basis”, in The New York Times‎