Contrary to popular belief, V1 is not the decision speed. Saying that it is would be misleading because V1 is not the point to begin making the decision to abort takeoff or not.
If the decision is not made before the aircraft reaches its V1 speed, the pilot will not initiate the stop early enough. The aircraft will subsequently be traveling at a speed higher than V1 when the stopping action is initiated, risking an accident and/or runway overrun.
Therefore, V1 could be called the “initiation speed”. The stopping action must be decided upon and initiated at or before the aircraft reaches V1 to ensure maximum safety of the aircraft and its crew.