tell it to the marines Definition

marine
adj

1. Belonging to or concerned with the sea.

Example: marine landscape
Thesaurus: maritime, oceanic.
2. Inhabiting, found in or obtained from the sea.

Example: marine mammal
3. Belonging or relating to ships, shipping trade or the navy.

Example: marine insurance
Example: marine architect
Thesaurus: maritime, nautical, naval.
4. Done or used at sea. See also maritime.

Example: marine compass
Thesaurus: oceangoing, seafaring, seagoing.

noun

1a. A soldier trained to serve on land or at sea;

Form: Marine (often)
1b. A member of the Royal Marines or the US Marine Corps.

Form: Marine (often)
2. The merchant or naval ships of a nation collectively.

Idiom: tell that to the marines (tell it to the marines)

colloq
An expression of disbelief and ridicule.

Etymology: 15c: from Latin marinus, from mare sea.