The word 'unjustifiable' is a layered negation built upon the concept of justice. Its core, the stem 'justifi,' originates from the Latin justificare, meaning "to make just," which itself combines justus (just, lawful) and facere (to do or make). The suffix '-able,' of Latin origin, was attached to form 'justifiable,' meaning "capable of being made right or defended." Finally, the Germanic prefix 'un-' was added to negate the entire construct, creating a term that literally means "not capable of being made just." This etymological journey reflects a logical progression from the action of justifying to the potential for that action, and finally to the absolute denial of that potential, arriving at its modern meaning of being indefensible or without reasonable cause.

Structure: un (not) + justifi (to justify) + able (capable of) - un: A prefix of Germanic origin (Old English, Old High German) meaning "not," used to form negatives. - justifi: A stem derived from the Latin verb justificare, meaning "to act justly" or "to make right," from justus (just) + facere (to make). - able: A suffix of Latin origin (-abilis), via Old French, meaning "capable of, fit for, or worthy of."