'securely-installed' originates from Modern English, specifically the combination of the adverb 'securely' and the past-participial/adjectival form 'installed'. 'securely' ultimately traces back to Latin 'securus', where 'se-' functioned as an intensive/negative element and 'cura' meant 'care'; 'installed' ultimately traces back to Latin 'installare', where the prefix 'in-' meant 'in' and the root related to placing or setting in position.

'secure' changed from Old French 'secur' and Middle English 'secur(e)' into the modern English 'secure', and 'install' changed from Old French/Old Italian forms like 'installer'/'installare' through Middle English to modern 'install', with the compound adjective formed in Modern English by combining the adverbial form with the past participle.

Initially, elements meant 'free from care' (from 'securus') and 'to place/put in position' (from 'installare'); over time the compound sense evolved to the current specific idea of 'placed or attached so as to be safe, stable, and not easily moved or tampered with'.