English
thereacross
From there + across.
Proto-Indo-European *tór ‘there’
Proto-Germanic *þar ‘at that place, there’
Proto-West Germanic *þār ‘there’
Old English þēr ‘there’
Middle English there
English there
Proto-Italic *kruks /*krukis
Latin crux ‘cross’
Old French croiz ‘in the form of a cross’
Middle English a-croiz
Middle English acros ‘in the shape of a cross’
English across
Today it means
adv Across that.
Language periods are conventional ranges, not dates for this word.
Etymograph / thereacross