Basin and Firth

Basin noun - A bowl-shaped vessel; usually used for holding food or liquids.

Firth and basin are semantically related In some cases you can use "Firth" instead a noun "Basin".

Firth noun - A part of a body of water that extends beyond the general shoreline.

Basin and firth are semantically related in arm of the sea topic. Sometimes you can use "Basin" instead a noun "Firth", if it concerns topics such as sea inlet, shoreline indentation.