In session
A court or organization is operating or functioning.The court has been in session since 9:00 AM.
In secret
Secretly.The meeting to talk about building the new hospital took place in secret.
In season
Currently available for sale, legally able to be caught or hunted.Cherries are in season now and they are very delicious.
In search of (someone or something)
Trying to find someone or something.I have been in search of a good family restaurant for several months now.
In ruin
Destroyed.Most of the hotels along the beach were in ruin after the hurricane.
In round numbers/figures
An estimated number, a figure that has been rounded off.I was able to learn, in round numbers, how much it would cost to paint our house.
In return for (someone or something)
As part of an exchange, as a way of paying someone back.In return for cleaning his carpets my friend helped me clean up our basement.
In retrospect
Thinking about the past with the knowledge that one now has.In retrospect, I would have handled the conflict with my friend very differently.
In particular
Specifically, especially.My father likes almost all sports but in particular he loves basketball.
In part
To some extent, partly.I think that the reason my uncle is not golfing well this year is in part because of his back problem.