A day off means day when you don't have to do your usual work. A free day is when you don't have any commitments, for example, we have one free day on the trip where there are no tours booked. An off day usually means you are not feeling well - I am having an off day today - I am feeling bit off today.

A DAY OFF is a holiday for someone,a day that they have taken off; 1)a day on which someone usually and regularly does not have work. 2)a day on which someone is allowed not to come into work. An off day for someone can mean same as day off,or that they are having a bad day at work. 1) informal if someone have an off day,they do not perform as well as usual. 2)(us)a day when people do not go to work

Day off;not present this day,either a scheduled break or due to dishonesty,illness or other emergency. Off(adverb)away from a place. Off day; meaning not performing well this day. Off(adjective)not upto standard,not so good or satisfactory as usual,"inferior or subnormal".

day off

I have a free day...