The exact definition of sentience is being able to perceive the outside world and react to stimuli. For example, insects can perceive light and use it to avoid dangers. Plants can sense light but can't react other than by growing a certain direction. Sunflowers and venus flytraps could be considered on the edge, but their capacity to sense and react is very specific. The word "sentience" refers to being animal-like in an organism's versatility of reactions.