gooseneck

Short definition from Wiktionary

Noun

1. 1
   Anything with a slender curved shape, resembling the neck of a goose, such as the shaft of some lamps.
2. 2
   The swivel connection on a sailboat located near the bottom of the mast that the boom attaches to. When a sailboat performs a tack or a jibe the gooseneck swings the boom from one side of the boat to the other.
3. 3
   Ellipsis of gooseneck barnacle.
4. 4
   Ellipsis of gooseneck loosestrife.