'axil' originates from Latin, specifically the word 'axilla', where 'axis' meant 'axis' or 'axle' and the diminutive suffix '-illa' meant 'small' (in Latin 'axilla' came to mean 'armpit').

'axil' changed from Late/Medieval Latin 'axilla' (used for 'armpit' or 'small axis') and was adopted in botanical Latin to denote the angle of a leaf, eventually entering English as the modern word 'axil'.

Initially it referred to 'armpit' or a 'small axis' in Latin, but over time it evolved into the botanical sense 'the angle between a leaf (or branch) and the stem where buds form'.