The word 'unsuccessfully' is a layered construction built upon the core Latin concept of 'success.' The Latin verb succedere, meaning 'to come after, to go well,' gave rise to the noun successus for a favorable outcome. In English, the adjective 'successful' was formed by adding the suffix '-ful,' meaning 'full of,' to this noun. To negate this quality, the Germanic prefix 'un-' was attached, creating 'unsuccessful.' Finally, the adverbial suffix '-ly,' tracing back to an Old English word for 'body' or 'form,' was appended to describe the manner of an action, completing the logical journey from a Latin idea of favorable progression to its modern English opposite describing an action done without achieving a desired result.

Structure: un (not) + success (achievement of an aim) + fully (in a manner of) - un: A prefix of Germanic origin (Old English un-), meaning "not." It functions as a negative particle. - success: A noun of Latin origin (successus, from succedere 'come close after'), meaning the accomplishment of an aim or purpose. It functions as the core semantic root. - fully: An adverbial suffix of Germanic origin (Old English -līce, from līc 'body, form'), meaning "in a manner of." It converts the adjective 'successful' into an adverb.