(n.) a mollycoddled young man
A mammothrept is a weak, spoilt child—and in particular, a mollycoddled young man.
That word was first recorded in English in 1601, in Ben Jonson’s satirical play Cynthia’s Revels. Although Jonson himself used it in this sense, the word mammothrept has since come to be used more figuratively to refer to someone who—perhaps like a spoilt child—lacks good judgment or knowledge due to their inexperience or immaturity.
The word is derived, via Latin, from the Greek mammothreptos, which literally described a child who was brought up by its grandmother; it’s formed from the Greek mamme, ‘mother’, and the verb trephein, meaning ‘to bring up’, or ‘to nourish’.