'ansiedad' originates from Latin, specifically the word 'anxietas', where the root 'anx-' related to feelings of distress or tightness.

'ansiedad' changed from Latin 'anxietas' to medieval Romance/Old Spanish forms (e.g. 'ansietat') and eventually became the modern Spanish 'ansiedad'.

Initially, it meant a state of distress or vexation ('anxietas'), and over time it evolved into the modern sense of 'anxiety'—worry, unease, or nervous anticipation.