'solitary-flowered' is a compound of 'solitary' and 'flowered'. 'Solitary' originates from Latin, specifically the Medieval/Latin adjective 'solitarius', where the root 'solus' meant 'alone'. 'Flowered' derives from Old French/Late Latin 'flor'/'flos', where 'flos, floris' meant 'flower'.

'solitary' changed from Latin 'solitarius' through Medieval Latin and Old French/Anglo-Norman into Middle English 'solitary'; 'flower' changed from Latin 'flos' to Old French 'flor' and then Middle English 'flower', with the participial/adjectival suffix '-ed' forming 'flowered'. The compound 'solitary-flowered' developed in English as a descriptive botanical adjective.

Initially the elements meant 'alone' (solus) and 'flower' (flos). Over time the compound came to mean specifically 'bearing a single flower (per stem or branch)' in botanical usage.