Thick skin is a metaphor for resilience and the ability to cope with difficult situations. The crossword solutions for the term 'thick skin' are 'RIND' and 'HIDE'. RIND is the outer layer of a fruit or vegetable, which is thick and tough, and HIDE is a thick layer of animal skin used for protection. Both of these words can be used to describe the concept of thick skin, as they both represent a strong and resilient outer layer.