Longman Dictionary of Contemporary English - key

~1 adj very important and necessary for success or to understand something  (Put your most experienced players in the key positions. | key points/questions/issues etc (=most important))  (You can summarize the key points of his speech in a few lines. | key mover/player (=most important person in achieving a result, change etc)) ~2 n 1 »LOCK« a small specially shaped piece of metal which you put into a lock and turn in order to lock or unlock a door, start a car etc 2 »IMPORTANT PART« the key the part of a plan, action, etc, that everything else depends on  (Concentration is the key to effective study.) 3 »MACHINE/MUSICAL INSTRUMENT« the part of a machine, computer, or musical instrument that you press with your fingers to make it work  (Press the ESCAPE key to exit. | She ran her fingers over the piano keys.) 4 »MUSICAL NOTES« a set of musical notes with a particular base note, and the quality of sound that they have  (a tune played in the key of C) 5 »MAP/DRAWING« the part of a map, technical drawing etc that explains the signs etc on it 6 »ISLAND« a small flat island, especially one near the coast of Florida  (the Florida Keys) 7 »TEST ANSWERS« the printed answers to a test or to the questions in a textbook1 that are used to check your work  (- see also low-key) ~3 v especially BrE to prepare a surface so that a covering such as paint will stick to it key sth in phr v to put information into a computer by using a keyboard1 (1)  (- see also keyed up) key sth to sth phr v T usually passive especially AmE to slightly change a system, plan etc so that it works well with something else  (be keyed to the needs of (=match the needs of))  (The daycare hours are keyed to the needs of working parents.)