'straightener' originates from the English word 'straight,' which comes from the Old English 'streht,' meaning 'direct or not crooked.'

'straight' evolved from the Old English 'streht' and combined with the suffix '-er' to form 'straightener,' indicating a tool or device that makes something straight.

Initially, it meant 'to make something direct or not crooked,' and over time it evolved to specifically refer to tools for straightening hair.