'auxin' originates from Greek, specifically the word 'auxein', where 'aux-' meant 'to increase' and '-in' is a common chemical suffix.

'auxin' was formed in Modern Latin/Neo-Latin as a coinage from Greek 'auxein' + the chemical suffix '-in' and was adopted into English in the early 20th century to name substances that promote plant growth.

Initially it meant 'that which increases' (i.e., causes growth); over time it became the technical term for plant hormones that regulate growth and development.