'mentally' originates from Latin, specifically the word 'mentalis,' where 'mens' meant 'mind.' 'Focused' comes from Latin 'focus,' meaning 'hearth' or 'fireplace,' which evolved to mean 'center of activity or interest.'

'mentalis' transformed into the Old French word 'mental,' and eventually became the modern English word 'mental.' 'Focus' was borrowed directly from Latin into English in the 17th century.

Initially, 'mentalis' meant 'of the mind,' and 'focus' meant 'hearth.' Over time, 'focus' evolved to mean 'center of interest,' and 'mentally-focused' now means 'having one's mind concentrated on a task.'