'untrendy' originates from the prefix 'un-' meaning 'not' and the word 'trendy', which comes from 'trend', meaning 'a general direction in which something is developing or changing'.

'trendy' evolved from the word 'trend', which was used in the 16th century to mean 'to turn or revolve'.

Initially, 'trend' meant 'to turn or revolve', but over time it evolved into its current meaning of 'a general direction in which something is developing or changing', and 'trendy' as 'fashionable'.