'saw-toothed' originates from English, combining 'saw' (originally from Old English 'sagu') and 'tooth' (from Old English 'toþ'), where 'saw' meant 'a toothed cutting instrument' and 'toþ' meant 'tooth'.

'saw' and 'tooth' come from Old English elements ('sagu' and 'toþ'); compounds meaning 'having teeth like a saw' developed in later English (Middle to Modern English) as 'saw-tooth' and the adjectival form 'saw-toothed' emerged from that compound.

Initially it described actual teeth or a tool with teeth ('saw' and 'tooth'); over time the compound adjectival sense 'having saw-like teeth or notches' has been the established meaning and remains so.