Coat/kəʊt/ Definition 1 of 5Pro Tip 1/3Weather Protection A 'coat' is often worn to guard against cold, wind, or rain when outside. Remember to wear a coat in bad weather to stay protected. Pro Tip 2/3Formal or Casual Coats can be formal like a trench coat or casual like a parka. He wore a formal coat to the job interview. Pro Tip 3/3Layers Beneath People often wear additional layers underneath a coat in colder climates. She put on a sweater under her coat for extra warmth.