A Middle English coinage (c. 1300) combining 'by' + Old Norse 'lágr' (low), PIE *legʰ- (to lie down) — replacing older 'beneþan' (beneath).
At a lower level or position than; under; beneath.
From Middle English 'bilooghe' or 'bilouhe' (c. 1200), a compound of 'bi-' (by, near) + 'looghe' (low). The element 'low' derives from Old Norse 'lágr' (low, short), from Proto-Germanic *lēgaz (lying flat, low), from PIE *legʰ- (to lie down, to lay), which also produced Latin 'lectus' (bed), Greek 'lékhomai' (to lie down), and Old Church Slavonic 'ležati' (to lie). The word 'below' is a relatively late English formation — Old English had no equivalent compound and instead used 'beneþan' (beneath), 'under,' or 'niþer' (nether). The
The word 'below' did not exist in Old English — it was coined in Middle English around 1300 by combining the prefix 'by-' with 'low,' a word borrowed from Old Norse during the Viking Age. Old English speakers used 'beneþan' (beneath) or 'under' for the same concept. 'Below' is thus partly a Viking contribution to English spatial vocabulary.