What is "cue bid"

In contract bridge, a cue bid (also, cuebid or cue-bid) is a term that applies to two types of bid:

• A bid of a suit that has already been bid by opponents.
• A slam-investigating bid made during an auction's later rounds that shows control of a suit. This is a traditional use of the term, but in the early 21st century the usage appears to be giving way to control bid.