key employee: An employee of extraordinary significance to the success and operation of a business; often a highly compensated officer, owner, or executive who manages critical processes, possesses unique skills and knowledge, controls a high proportion of customer relationships or sales, is deemed likely to be very difficult to replace, and who is often given incentives to remain with the business.

key person insurance; key employee insurance: Life insurance that protects a company against the loss of business or revenue likely to result from the death of a key officer or employee.

keyword: A word or phrase that people use in online searches to describe the type of information they’re seeking. Web site owners try to use keywords throughout their sites in an effort to optimize the chance that they’ll appear high in relevant search results; search engine owners sell high search placement to marketers so their ads will appear on keyword search result screens.

kinesthetic: Hands-on learning in which the instructed is allowed to use the item they're learning about.