Jaw-dropper

n.energetic, joyfulplayful

What it means

A person, sight, or achievement that causes astonished admiration.

Reach for it when naming an exceptionally impressive result in lively informal praise

The final lantern display was a jaw-dropper against the dark harbor.

playful
knockout
appearance or performance is dazzling in casual speech
not when Knockout is unsuitable when physical or romantic overtones could distract.
playful
showstopper
one feature commands attention and halts the normal flow
not when Showstopper suggests public display and can feel theatrical for a private achievement.
everyday
stunner
striking beauty or excellence deserves quick informal praise
not when Calling a person a stunner can reduce them to appearance; avoid it professionally.
warm
marvel
ingenuity or beauty invites sustained wonder
not when Marvel is gentler and less tied to the instant shock implied by jaw-dropper.
formal
masterpiece
exceptional artistic execution can be defended
not when Masterpiece claims enduring top-tier quality, not merely a startling first impression.
formal
revelation
the result overturns expectations by revealing unexpected quality
not when Revelation stresses discovery rather than sheer visual impact.
literary
spectacle
large-scale visual impact is the defining feature
not when Spectacle can be empty display and does not necessarily praise quality.

absolute jaw-dropper
The restored ceiling was an absolute jaw-dropper in the morning light.
visual jaw-dropper
A visual jaw-dropper greeted visitors at the end of the narrow corridor.
a genuine jaw-dropper
The apprentice's final cabinet proved a genuine jaw-dropper.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.