daub

Concise Oxford English Dictionary © 2008 Oxford University Press:
daub /dɔːb/

▶verb carelessly coat or smear with a thick substance.

■ spread (a thick substance) on a surface in such a way.

▶noun

• 1 plaster, clay, etc. mixed with straw and applied to laths or wattles to form a wall.

• 2 a patch or smear of a thick substance.

• 3 a painting executed without much skill.

– derivatives
dauber noun.

– origin ME: from OFr. dauber, from L. dealbare ‘whiten, whitewash’, based on albus ‘white’.