Poison-berry is a term that typically refers to a type of shrub or bush that produces toxic berries, such as the deadly nightshade. Some possible synonyms for this word might include terms like venomous berry, lethal fruit, or toxic drupe. Other options could include phrases like deadly berry, dangerous seed, or harmful fruit. Ultimately, the best synonym for poison-berry will depend on the context in which it is being used and the specific type of plant it refers to. However, no matter what term is used, it is important to always exercise caution around toxic plants and berries in order to avoid illness or even death.