Unrelaxed comes from un- ('not') + relaxed, from relax, from Latin relaxare ('to loosen, stretch out'), from re- ('back') + laxare ('to loosen'), from laxus ('loose'). In current use it is an adjective meaning "tense; not at ease". That sense is explained by the older material without requiring a speculative semantic step: the inherited or borrowed base supplies the field of meaning, while the English formation fixes its modern role. The prefix un- is negative or privative, marking the absence, denial, or opposite of the base idea. The surface form is compositional: its joined elements remain visible in the modern word. The historical chain includes Old English un- and Latin laxus. Related English forms include relax, relaxed, and relaxation. As a result, the modern word is best read as a negative, privative, or reversative formation built on a historically older base.