Teen
Part of speech: noun
Definition: A teenager, a person between 13 and 19 years old. Grief; sorrow; affliction; pain - Geoffrey Chaucer, Edmund Spenser
Part of speech: verb
Definition: To excite; to provoke; to vex; to afflict; to injure. - Piers Plowman To hedge or fence in; to enclose. - Halliwell?
Immature
Part of speech: adjective
Definition: Not fully formed or developed, unripe.Childish in behavior.
Example sentence: Everyone knows that life isn't fair. Saying it's not fair suggests that you think life is supposed to be fair, which makes you look immature and naive.