inlet

Short definition from Wiktionary

Noun

1. 1
   A body of water let into a coast, such as a bay, cove, fjord or estuary.
2. 2
   A passage that leads into a cavity.

Verb

1. 1
   To let in; admit.
2. 2
   To insert; inlay.
3. 3
   To carve the wooden stock of a firearm so as to position the metal components in it.