'angularly' originates from English, specifically the adjective 'angular' plus the adverbial suffix '-ly', where the root traces to Latin 'angulus' meaning 'corner, angle'.

'angulus' in Latin yielded 'angularis', which passed into Old French as 'angulaire' and into Middle English as 'angulere/angulare' -> modern English 'angular'; adding '-ly' formed the modern adverb 'angularly'.

Initially, the base idea was 'having corners/angles'; as an adverb it came to mean 'in an angular manner' and, by extension, 'with respect to angle' in technical contexts.