white cap—
1. (pl.) white foam on the crests of waves (in stormy weather):
- We had a strong head wind … the surface of the lake was covered with white-caps.
2. name for several birds having a white patch on the head:
- The male [Redstart] is called “whitecap” in Shropshire, from its white forehead.
3. name for species of mushroom:
- These are the common mushrooms you see in almost every supermarket these days. White caps are used raw in salads, and in cooking.
white hat—
1. (U.S. Navy) an enlisted man:
- There’s a white hat out here who has gone crazy.
2. (coll.) a good and righteous man:
- Nixon clung to the original plan against the urging of Garment, and other “white hats.”