The term 'WORK AT, AS A TRADE' can be summarized by the three letter word 'PLY'. This word is used to describe a person who works in a particular field or profession, usually as a result of having trained in that area. It is often used to refer to someone who has a specific skill set or expertise in a certain area. For example, a plumber would be said to PLY their trade in plumbing, or a carpenter would PLY their trade in carpentry.