Flight Instructor with student reported a near miss with an aircraft that was taking off on the opposite direction runway at a non-towered airport and was not making any radio transmissions.

Narrative

Working with a student on short field take-off and landing training in the traffic pattern at FNL. Two aircraft were working the traffic pattern for Runway 33 with winds at 150/4; using Runway 33 per chart supplement guidelines as preferred runway for light winds. At approximately XA45; on the second or third pattern; on a short field climb out after touch and go; we noticed an opposite direction ADS-B return taking off on Runway 15 at FNL. The following aircraft in the traffic pattern aborted their touch and go take-off after noting take-off traffic in the opposite direction; an Aircraft Y. The opposite direction of traffic did not make any radio transmissions on taxi; take-off; or climb out.Due to runway slope and pitch on the short field climb out; the opposite direction traffic was not visually observed during our touch and go and climb out. Subject aircraft initiated take-off roll opposed to and underneath our aircraft. The following aircraft was able to visually note the opposite direction take-off and abort take-off and avoid the subject aircraft. There was no indication that the subject aircraft was aware of ongoing pattern operations; and simply took off on their chosen runway despite chart supplement operating guidelines for the airport; and made no radio calls during their entire local operation. Head-on collision with two aircraft was narrowly averted due to careless and negligent operation by the subject aircraft.