The phrase "thick coat" refers to a type of clothing, specifically an outer garment that is made from material that is thick and heavy. This kind of coat provides warmth and protection against cold weather conditions by trapping air close to the body, insulating it from the chilly temperatures outside. The term can also be used figuratively to describe someone who has a lot of something - for example, "He's got a thick skin" means that he is emotionally resilient and not easily affected by criticism or negative comments.