What type of trap is known as a "Bottle-trap"?

A bottle trap is indeed classified as a single fixture trap. This type of trap is designed specifically for use with individual plumbing fixtures, such as sinks or lavatories, and is used to prevent sewer gases from escaping into the living space while allowing waste water to flow out.

Bottle traps are compact and have a distinctive design resembling a bottle, with the curved section acting as the water seal. The design facilitates easy cleaning and maintenance, making it a preferred choice for situations where a traditional P-trap might not fit due to space constraints.

It’s important to note that single fixture traps, including bottle traps, are generally used in applications where the plumbing does not serve multiple fixtures in a gravity drainage system. This distinguishes them from traps like P-traps or S-traps which are used in more complex plumbing setups that may involve multiple connections or longer runs of piping.