Sentence:  He should feel lucky I agreed to test out this <WSD>bird-nesting</WSD> custody arrangement this month. It was a huge inconvenience for me to have the kids staying full time in the house while Mark and I traded time living there. 
Meaning of the word marked with <WSD> tags:  A custody arrangement in which the child of divorced parents remains in one home while the parents take turns to move in and out.