'somebody' originates from Old English elements, specifically 'sum' (Old English) + 'bodig' (Old English 'body'), where 'sum' meant 'some' or 'one' and 'bodig' meant 'body' or 'person'.

'somebody' appeared in Middle English as 'sombody' or 'som body' formed by joining 'some' + 'body', and it eventually became the modern English 'somebody' (plural 'somebodies').

Initially it meant 'some person' or 'a certain person', and that core meaning has remained; over time it also acquired senses emphasizing a person's importance (e.g. 'become somebody').