Jetty and Obsidian

Jetty noun - A structure used by boats and ships for taking on or landing cargo and passengers.

Obsidian and jetty are semantically related In some cases you can use "Obsidian" instead an adjective "Jetty".

Obsidian noun - Acid or granitic glass formed by the rapid cooling of lava without crystallization; usually dark, but transparent in thin pieces.

Jetty and obsidian are semantically related in black topic. Sometimes you can use "Jetty" instead an adjective "Obsidian".