A gob is an informal, slightly crude word for a lump or blob of something, especially something wet, sticky, or messy. You might see a gob of mud stuck to your shoe after walking through a puddle, or scrape a gob of peanut butter off a knife. Scientists studying volcanoes watch gobs of molten lava ooze down mountainsides.

The word sounds like what it describes: short, blunt, and a bit gross. It's the kind of word you'd use when “piece” or “bit” feels too polite for the messy reality. If your little sister gets a gob of maple syrup in her hair at breakfast, everyone knows exactly what happened without needing a detailed explanation.

In British slang, gob also means the mouth, so “shut your gob” means “be quiet.” And in very old American slang, a gob was a sailor in the U.S. Navy, though you'll mostly encounter this usage in old books or movies. The messy lump meaning is by far the most common today.