English
fifthly
From fifth + -ly.
A compound of fifth + -ly
Proto-Indo-European *pénkʷe ‘five’
Proto-Indo-European *penkʷtós
Proto-Germanic *fimftô
Old English fīfta
Middle English fifthe
English fifth
Today it means
adv In the fifth place; fifth in a row.
Language periods are conventional ranges, not dates for this word.
Etymograph / fifthly