means A person who secretly and illegally transports goods or people across a border to avoid taxes, duties, or laws.

from From the Low German or Dutch 'smuggeln' (to transport illicitly), a cousin of Old Norse 'smjuga' — to creep through a hole or wriggle into a tight space. The word slipped into English in the late 1600s alongside a booming trade in untaxed tea, brandy, and tobacco, and you can still feel that wriggling, slinking-through-the-gap sense buried in the root.