'self-centredly' originates from English, specifically formed from 'self' + 'centred' + the adverbial suffix '-ly', where 'self' meant 'one's own person' and '-ly' forms an adverb.

'self-centred' developed from the adjective 'self' (Old English 'self') combined with 'centred' (from Latin via Old French and Middle English 'centre' < Latin 'centrum' < Greek 'kéntron'), and the adverb was created by adding '-ly' to make 'self-centredly'.

Initially components like 'centre' referred to a physical center (from Greek 'kéntron'), but the compound came to mean placing oneself figuratively at the center; 'self-centredly' now means acting as if oneself is the center of attention or concern.