'red-cell' is a Modern English compound formed from the adjective 'red' and the noun 'cell' (from Latin 'cella'), where 'red' originally meant 'red' and 'cella' meant 'a small chamber or room'.

'red-cell' developed from the two-word phrase 'red cell' in English; 'red' comes from Old English 'rēad', while 'cell' comes from Latin 'cella' (via Old French), and the compound usage became established in medical and scientific contexts in modern English.

Originally a simple descriptive combination meaning 'a cell that is red', it evolved into a technical term referring specifically to the blood cell type 'erythrocyte' and to adjectival uses in medical compounds.