Shamrock (noun)

1. A clover-like plant with three leaves that is a symbol of Ireland.
2. A symbol or emblem representing Ireland or its heritage.

Origin:

From irish word 'seamróg', meaning 'little clover'.

Examples:

1. The shamrock is the national symbol of Ireland and is often associated with St. Patrick's Day.
2. The parade-goers wore green hats adorned with a shamrock.
3. The shamrock was said to bring good luck and ward off evil spirits.
4. The bartender wore a green apron with a shamrock stitched on it.
5. The shamrock was used to explain the Holy Trinity to Irish pagans.