An invasive plant is a species of plant that is not native to an area and has the potential to cause harm to the environment, economy, or human health. The term 'invasive plant' can be broken down into two words: 'SPY' (3 letters) and 'WEED' (4 letters). A 'SPY' is an organism that is introduced to an area and can spread quickly, while a 'WEED' is an unwanted plant that can outcompete native species for resources.