to not notice what is happening around you, usually because you are thinking about something else.

She just sat and stared out of the window most of the time - she seemed to be in another world.

I don't think you even heard me, did you? You're in a world of your own.

• put at odds with someone
• put away
• put away someone
• put away something
• put back into
• put back into something
• put back on the rails
• put back on track
• put back up
• put behind
• put behind someone
• put behind something
• put behind you
• put best foot forward
• put cards on the table
• put down roots
• put down to experience
• put feet up
• put finger on
• put finger on something
• put flesh on
• put flesh on something
• put flesh on the bones of
• put flesh on the bones of something
• put foot down