Mexican jumping bean

1 8.3

A seed from a Mexican shrub that jumps when a baby moth moves inside

noun
/ˈmɛksɪkən ˈdʒʌmpɪŋ biːn/

: frijolito saltarín

I watched in amazement as the Mexican jumping beans twitched and moved in their container, making it look like they were alive.

Examples

The human Mexican jumping bean strikes again.

Fiction book (1995)
He had brought me a little jar of Mexican jumping beans.

Fiction book (1991)
My brother bragged that I must have escaped the anthropoid chain and mutated into a line of kangaroos who lived on Mexican jumping beans.

Fiction book (1994)
My friend brought a jar filled with Mexican jumping beans to the party, and everyone was fascinated by how they jumped around.
For her science project, she decided to study the behavior of Mexican jumping beans and how the larvae make the seeds jump.

Synonyms

jumping bean

vsMexican jumping bean

1 7.3

A seed that moves because a baby moth lives inside it

has identical meaning but stresses Mexican origin in its name

jumping seed

vsMexican jumping bean

Specialized

9.9

A seed from Mexican shrubs that moves because a baby moth inside wiggles

is the same but uses a general description without botanical names

Surface Forms

Mexican jumping bean singular

Mexican jumping beans plural

Morphology

Mexican + jumping + bean

The phrase is compositionally built from 'Mexican' (origin), 'jumping' (moving by jumping), and 'bean' (a seed), so a learner who knows those words will infer it refers to a bean that jumps or moves and likely comes from Mexico. The specific biological cause (a moth larva inside) is extra detail but not required for a B1 learner to understand the basic meaning.

Etymology

The noun Mexican jumping bean comes from seeds from Mexico that seem to move because a tiny moth larva lives inside them. The larva pushes and makes the bean 'jump', so people called it a jumping bean meaning 'a seed that seems to move'.