The word 'sultry' originates from the late 16th century, evolving from the now-obsolete verb 'sulter', meaning 'to swelter'. This verb is a variant of 'swelter', which in Middle English meant 'to be faint or oppressed by heat', and is related to the Old English 'sweltan', meaning 'to die or perish'. The semantic journey connects the literal experience of oppressive, stifling heat to a figurative sense of passionate, smoldering intensity. This evolution reflects how physical sensations of heat and discomfort were metaphorically extended to describe atmospheres charged with emotion or sensuality.

The word 'sultry' is a simplex word derived from the obsolete verb 'sulter', a variant of 'swelter', which itself comes from Middle English 'sweltren'.