'soother' originates from Old English, specifically the verb 'sōthian,' where 'sōth' meant 'truth' (and later 'that which is true').

'sooth' (Old English 'sōth') developed into Middle English 'soothe'/'sothen' with senses shifting toward comfort; the agent noun formed with '-er' produced 'soother' meaning 'one that soothes.'

Initially related to 'truth' or 'to prove true,' the word's sense shifted over time to mean 'to ease or comfort,' and today 'soothe'/'soother' primarily convey calming or relieving meanings.