Hawser or hawse pipe
The opening of a volcano is called the vent.The opening of a volcano is called a vent.
It is called the hatchway. If it is a round opening, it is called a scuttle. If it is a square opening it is called a hatch. Depending on the vessel and the location they can be "dogged" open.
The opening is called a stomata, which is regulated by two guard cells.
The opening of a volcano is called the caldera.
It is called the crater
The opening is called an estuary.
Olivia actually sings the opening song, but I don't know what it is called.
Really, it could be called both. Both are correct.
The external opening is the urethra. Not really. The urethra is the tube that leads from the bladder. The opening is called the urethral opening.
They are called "jack studs" above the opening and "king studs" below the opening. These studs help support the header above the opening in a framed wall structure.
It is called the osculum.
The opening of a letter is called a salutation. It typically includes a greeting, such as "Dear [Name]," followed by a comma.