What does the word tangent mean in the sentence the formal gardens were designed so that each large, circular flower bed had it own tangent gravel path

Throughout the giver, author lois lowry renames many everyday terms. eleven-year-olds are "elevens," babies are "newchildren," stuffed animals are "comfort objects," and families are called "family units." what is the purpose of these alternate labels? what effect do they have on the story?