'slowly-checked' originates from the combination of 'slowly' and 'checked', where 'slowly' is derived from the Old English 'slāw' meaning 'slow' and 'checked' from the Middle English 'chekken', meaning 'to stop or restrain'.

'slowly' evolved from the Old English 'slāw' and 'checked' from the Middle English 'chekken', eventually forming the modern English compound adjective 'slowly-checked'.

Initially, 'slowly' meant 'at a slow pace' and 'checked' meant 'to stop or restrain', but over time, the compound 'slowly-checked' evolved to mean 'verified at a slow pace'.