Unwanted growth is a term used to describe the presence of plants that are not desired in a particular area. Two examples of this type of growth are crabgrass and WEED, both of which have nine and four letters respectively. Crabgrass is a type of grassy WEED that is difficult to control and can spread quickly, while WEED is a broad term used to describe any plant that is considered to be a nuisance or undesirable.