keystone

Plural: keystones

Noun

• The central, top stone of an arch, locking the others in place.
• a central cohesive source of support and stability
  • "the keystone of campaign reform was the ban on soft money"
• the central building block at the top of an arch or vault
• The top stone of an arch.
• Something on which other things depend for support.
• A native or resident of the American state of Pennsylvania.
• A retail price that is double the cost price; a markup of 100%.
• The combination of the shortstop and second baseman.

Verb

• To distort (an image) by projecting it onto a surface at an angle, which for example causes a square to look like a trapezoid.
• To double the cost price in order to determine the retail price; to apply a markup of 100%.

Examples

• His final word was the KEYSTONE of his Words With Friends victory, securing all his points.

Synonyms

anchor, backbone, headstone, key, linchpin, lynchpin, mainstay