From Middle English 'bi cause' (by cause), calqued from Old French 'par cause de' — the phrase fused into one conjunction by the 15th century.
For the reason that; since.
From Middle English 'bi cause' (by cause), a calque of Old French 'par cause de' (by reason of). The 'cause' element derives from Latin 'causa' (cause, reason, lawsuit, case), which has no certain PIE etymology though some connect it to *keh₂us- (to strike) or to a root meaning 'to cut (a case).' The phrase 'by cause that' gradually fused into the single conjunction 'because' in the 14th century. Before this calque arrived, Old English expressed causality with 'for þǣm þe' (for that which) or 'for þȳ þe' (for the reason
The internet-era use of 'because' followed directly by a noun — 'I can't come because reasons' or 'because science' — was named the American Dialect Society's Word of the Year in 2013. This 'because + noun' construction collapses the traditional 'because of [noun]' structure, and linguists call it the 'prepositional because.' It is a genuinely new grammatical development, the first major structural shift for a 700-year