'loosely-installed' is a compound of the adverb 'loosely' and the past participle 'installed'. 'Loosely' comes from English 'loose' + suffix '-ly' (Old English 'lōs' meaning 'free, loose'), and 'installed' comes from the verb 'install' (from Old French enstaller/installer, ultimately from Latin roots meaning 'place in a stall').

'loose' developed from Old English 'lōs'; the adverbial form 'loosely' is formed by adding the adjective-to-adverb suffix '-ly'. 'Install' came into English via Old French (enstaller/installer) from Latin elements (related to 'stallum' meaning 'stall, place'), yielding the past participle 'installed'. The modern compound phrase 'loosely-installed' is a transparent combination formed in Modern English by joining these elements.

Originally, the components referred to 'not tight' ('loose') and 'to place or set up' ('install'); together they have come to mean 'placed or fixed in a way that is not tight or secure' without significant shift in the basic senses of the parts.