(まんねん)

まんねん
noun, prefix
ten thousand years; perennial; perpetual
time-general
1. ten thousand years; perpetual; perennial
Literally 'ten thousand years.' Used as a prefix in compounds to mean 'perpetual' or 'perennial,' and often, half-jokingly, 'forever stuck in one state.'
富士山(ふじさん)万年(まんねん)(ゆき)ある
Mt. Fuji has perpetual snow.
(かれ)万年(まんねん)係長(かかりちょう)だ。
He's been a section chief forever (never promoted).
(あに)万年(まんねん)(どこ)で、布団(ふとん)いつも()っぱなしだ。
My brother never puts his futon away—it's permanently laid out.

Literally 'ten thousand years.' Beyond the literal number, it works as a prefix meaning 'perpetual' or 'perennial,' and often 'forever stuck in one state'—frequently with a humorous or resigned tone.

Compounds

Usage

The '10,000' here is figurative, meaning 'countless' or 'endless,' much like 'a thousand' in English expressions.