'tactless' originates from the word 'tact', which comes from Latin 'tactus', meaning 'touch'. The suffix '-less' indicates the absence of something.

'tactless' evolved from the combination of 'tact' and the suffix '-less', forming the modern English word 'tactless'.

Initially, 'tact' referred to the sense of touch, but it evolved to mean sensitivity in dealing with others, leading to 'tactless' meaning lacking that sensitivity.