jack-in-the-box
UK[ˈdʒæk ɪn ðə ˌbɒks]US[ˈdʒæk ɪn ðə ˌbɑːks]
n
A toy consisting of a box with a figure of a man on a spring inside that jumps out when the lid is opened.
Etymology
The term 'jack-in-the-box' originated in the 16th century, predating the modern toy. It initially referred to a swindler who would cheat tradesmen by substituting an empty box for one full of money. The name 'Jack' was a common generic name for any man, much like 'John Doe'. By the early 18th century, the term was applied to the toy, which features a comical figure (Jack) concealed inside a box, capturing the surprise element of the original deceit. The phrase thus evolved from describing a deceptive person to naming a playful, surprising object, solidifying its place in the lexicon as a single conceptual unit.
Analysis
This is a compound noun phrase, not a single word formed from classical morphemes. It is a fixed expression where the individual words ('jack', 'in', 'the', 'box') have lost their independent meanings to form a single lexical unit.
Examples
The toddler squealed with delight when the clown popped out of the jack-in-the-box.
The old jack-in-the-box, with its faded paint and creaky music, was a cherished family heirloom.
The comedian's entrance was as surprising as a jack-in-the-box popping open.