Definition: to breathe noisily
Snotter is a dialectal British word, and, as is so often the case with dialect words, carries a certain trenchant charm. It also has a variety of closely-related meanings, as it may be used to refer to snoring, sniveling, sniffing, snorting, or simply as another way to say snot.
“Oo, ‘deed, my leddy, he’s just quite silly-wise,” responded the dame, in a whining melancholy key; “he just lies there snottering awa’,” pointing to the bed.
—Susan Ferrier, The Inheritance, 1824