The term 'slender; thin' can be described by the word 'LEAN', which is a four-letter word. LEAN is an adjective that is used to describe something that is thin or slender in shape or size. It is often used to describe people who are thin or have a slim figure. LEAN can also be used to describe food that is low in fat or calories. In general, the term 'LEAN' is used to describe something that is thin or slender.