'badly-managed' is a compound of the adverb 'badly' + the past-participial adjective 'managed'. 'Badly' derives from 'bad' + '-ly' (Old English roots), meaning 'in a bad way'. 'Manage' comes from Italian 'maneggiare' meaning 'to handle', ultimately from Latin 'manus' meaning 'hand'.

'manage' passed into English via Old French (e.g., 'mesnager'/'managier') and Middle English as 'manegen'/'manage', developing the senses related to handling, directing, and controlling. 'Bad' is Old English in origin and formed the adverb with the suffix '-ly'. The compound 'badly managed' formed by combining these elements describes something handled poorly.

Initially, 'manage' had the concrete sense 'to handle (by hand)'; over time it broadened to mean 'to direct or control'. 'Badly' has long meant 'in a bad way'; combined, the phrase's meaning has remained stable as 'handled or directed poorly'.