'externally-triggered' originates from the combination of 'external' and 'triggered', where 'external' comes from Latin 'externus' meaning 'outside', and 'triggered' is derived from the word 'trigger', which comes from Dutch 'trekken' meaning 'to pull'.

'Externally-triggered' evolved from the combination of 'external' and 'triggered', which were used separately in Middle English and later combined in modern English.

Initially, 'external' meant 'outside' and 'triggered' meant 'activated', and this meaning has largely remained the same in modern usage.