For the nose (actor CV- + muɴ-) to excrete nasal mucus.
Mun'u'ūtog: focus is on the nose which continuously excretes mucus; by ellipsis focus is also on a person.
Mun'u'ūtog hi Dongpop ti na'ālog.
Dongpop is continuously excreting nasal mucus because she has a cold.