Inlet
Inlet , noun
1.
A passage by which an inclosed place may be entered; a place of ingress; entrance;
a narrow waterway leading into a harbor.
Doors and windows, inlets of men and of light.
2.
A bay or recess, as in the shore of a sea, lake, or large river; a narrow strip of water running into the land or between islands.
3.
That which is let in or inlaid; an inserted material.
Inlet is also used adjectively, as in inlet pipe, inlet valve, etc.