'stalwart' originates from Middle English, specifically the word 'stalward' (or 'stalwart'), where the element 'stal-' related to a fixed position or steadiness and the suffix '-ward' (from Old English 'weard') meant 'guardian' or 'in the direction of/one who wards'.

'stalwart' changed from Middle English 'stalward' (formed from older Germanic elements, including Old English 'steall' or related roots meaning 'place/position' and 'weard' meaning 'guardian') and eventually became the modern English word 'stalwart' with its current spelling and sense.

Initially it meant someone who 'stood firm' or acted as a guard/steadfast figure (i.e., 'standing firm in place' or 'a reliable guardian'), but over time it evolved to the broader current meanings of 'loyal, dependable supporter' and 'physically strong or sturdy'.