'yearly' originates from Old English, specifically the word 'ġēarlic,' where 'ġēar' meant 'year' and '-lic' was a suffix meaning 'like' or 'pertaining to.'

'ġēarlic' transformed into the Middle English word 'yerly,' and eventually became the modern English word 'yearly.'

Initially, it meant 'pertaining to a year,' and this meaning has largely remained the same in modern usage.