the small particles of loose tea leaves etc... that have could not be filtered out of a freshly brewed cup, mug, or tea pot of hot tea when loose tea is used instead of tea bags.
Sarah, the teacher's assistant: Sorry Professor, that's just loose tea flotsam. I'll get you another cup. Perhaps, you should use tea bags instead of loose tea leaves for your morning cup of tea?
Professor Stiffupperlip: PERISH THE THOUGHT!