English
hollow earther
From hollow + earth + -er.
Proto-Indo-European *ḱel- ‘to cover, hide’
…
Proto-Germanic *hulwiją ‘depression, hollow’
Proto-West Germanic *holh
Old English holh ‘a hollow’
Middle English holow
English hollow
Proto-Indo-European *h₁er- ‘earth’
Proto-Germanic *erþō ‘dirt, ground, earth’
Proto-West Germanic *erþu ‘earth’
Old English eorþe ‘ground’
Middle English erthe ‘earth’
English earth
Today it means
noun Someone who believes the Earth is hollow.
Language periods are conventional ranges, not dates for this word.
Etymograph / hollow earther