1) to be next to (something) (adjoin)

2) the finger next to the thumb (forefinger)

3) a room in a large house next to the kitchen, where dishes, pots etc are washed up (scullery)

4) clothing worn next to the skin (underwear)

5) (GB) an article of underwear worn on the upper part of the body next to the skin (US = undershirt); (US) a waistcoat; to give (a person) (something) as a fixed right (vest)