Trial/ˈtraɪəl/ Definition 1 of 4Pro Tip 1/3Product Testing Used for assessing performance or quality of new products. After rigorous trials, the smartphone was deemed reliable. Pro Tip 2/3Medical Research Critical for developing and approving medical treatments. The clinical trials for the vaccine will start next year. Pro Tip 3/3Temporary Use Often implies a period where something is used before final decision. We're on a trial period with the new software.