Plummy

adj.joyful, calmplayful

Meaning 1

Rich, rounded, and resonant in sound, especially in a voice.

Reach for it when describing a full, polished vocal quality with an upper-class British association

A plummy contralto voice gave the old ballad depth and warmth.

warm
rich
for a full sound with satisfying depth and overtones
not when Rich also describes flavor, color, and content, so context must establish sound.
professional
resonant
when a voice has depth and carries strongly
not when Resonant lacks the social and stylistic associations of plummy.
professional
rounded
when smooth balance across a voice's tone is the focus
not when Rounded is technical and does not imply volume or social accent.
literary
sonorous
if a deep, imposing sound deserves elevated description
not when Sonorous is grander and may feel heavy rather than pleasant.

Especially desirable, rewarding, or choice.

Reach for it when marking an opportunity or role as unusually attractive

The plummy assignment offered months inside the newly opened archive.

professional
coveted
if many people actively want the opportunity
not when Coveted describes demand and may introduce rivalry absent from plummy.
formal
choice
for an opportunity selected as one of the best available
not when Choice is concise but can sound dated in this adjective use.

plummy voice
The narrator's plummy voice suited the stately country-house scenes.
plummy tones
Plummy tones rolled through the hall during the comic announcement.
plummy role
The revival gave its veteran actor a plummy role full of sharp dialogue.

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