Bolthead

noun

1. A long straight-necked glass vessel for chemical distillations. Also called matrass and receiver.
2. A long, straight-necked, glass vessel for chemical distillations; -- called also a matrass or receiver.
3. The head of a bolt.
4. A round-bottomed flask with a long neck (used especially for distillation)
5. The head of a bolt.