'gland' originates from Latin, specifically the word 'glandula,' where 'glandula' meant 'acorn' or 'gland.' 'Opening' originates from Old English, specifically the word 'openung,' where 'openung' meant 'an opening or aperture.'

'gland' changed from the Latin word 'glandula' and eventually became the modern English word 'gland.' 'Opening' transformed from the Old English word 'openung' and eventually became the modern English word 'opening.'

Initially, 'gland' meant 'acorn' or 'gland,' and 'opening' meant 'an opening or aperture.' Over time, 'gland-opening' evolved to specifically refer to the orifice of a gland.