The ship built by Noah according to God's command, as related in the bible.
[PJC]

2. (Zoöl.) A marine bivalve shell (Arca Noæ), which somewhat resembles an ark, or ship, in form.

3. A child's toy, consisting of an ark-shaped box containing many different wooden animals.

4. (Fig.) Anything having a wide and representative assortment of people or objects of a particular class; as, the bar scene in Star Wars was a Noah's Ark of almost every imaginable alien form..
[PJC]

Webster 1913 Dictionary edited by Patrick J. Cassidy