Unmitigated comes from un- ('not') + mitigated, past participle of mitigate, from Latin mitigare ('to soften, make mild'), from mitis ('mild, soft') + agere ('to do, make'). The historical chain includes Old English un-, Latin mitigare, and Latin mitis. The quoted older senses, "not", "to soften, make mild", "mild, soft", and "to do, make", supply the semantic anchors for unmitigated. The formation is best read as compound, participial, and borrowed: the word unmitigated carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "absolute; not lessened or softened in any way". English derivatives include unmitigatedly; related English forms include mitigate, mitigation, and mitigated. The result is a adj whose etymology preserves both the older form and the later English specialization.