Let's Compare Mucosa and Serosa. 1  MUCOSA VS.  Mucosa. The mucous membranes (or mucosae or mucosas; singular mucosa) are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. mucosa \mucosa\ n.
Definition of dropper for English Language Learners. : a glass or plastic tube that is used to measure out liquids by drops.
Definition of drop for Students. 1  1 : a small amount of liquid that falls in a rounded shape. 2  2 drops plural : liquid medicine measured by drops ear drops. 3  3 : something (as a small round candy) that is shaped like a liquid drop.  4 : a small amount I'll have just a drop of 1  tea. 5 : the distance of a fall a 20-foot drop.