mole
noun /məʊl/
  /məʊl/
 - a small animal with dark grey fur, that is almost blind and digs tunnels under the ground to live in see also molehillTopics Animalsc2Oxford Collocations Dictionarymole + verb- burrow
- dig
- tunnel
- …
 
- a small dark brown mark on the skin, sometimes slightly higher than the skin around it compare freckleTopics Appearancec2Oxford Collocations Dictionaryadjective- hairy
- raised
 - remove
 
- a person who works within an organization and secretly passes important information to another organization or country- They suspected that a mole had been planted in the organization.
- A police mole working inside the company had supplied them with the details.
 Oxford Collocations Dictionaryverb + mole- plant
 
- (chemistry) a unit for measuring the amount of substance
Word Originsense 1 and sense 3 late Middle English: from the Germanic base of Middle Dutch and Middle Low German mol.sense 2 Old English māl ‘discoloured spot’, of Germanic origin.sense 4 early 20th cent.: from German Mol, from Molekul, from Latin molecula, diminutive of Latin moles ‘mass’.