Commentary for Genesis 7:22

נשמת רוח חיים means the breathing of the breath of life.

כל אשר נשמת רוח חיים באפיו, both the words נשמת and רוח are in a construct mode belonging to the word חיים, as if the Torah had written נשמת חיים ורוח חיים. Other examples of such a construction are found in Ezekiel 31,16 מבחר וטוב לבנון, “the choicest and best of Lebanon.” Or, Job 20,17 נהרי נחלי דבש וחמאה, “the streams, the rivers of honey, the brooks of cream.” The Torah, when referring to man, speaks of נשמת, whereas when speaking of the animals it describes their essence of life as רוח חיים.