You heard a catchy new song a few days ago with your wife that
you both liked. Today you were singing the song quietly to
yourself while you worked. You want to tell her about it, so you
confess this to her. I've been humming that song all day. To
"hum" a song means to make the notes of the song with your mouth
closed, without saying the words. People usually do this quietly
for their own entertainment. People use this phrase to describe
something that they did several times in a day, and that they
might continue doing. (Print this lesson)