key (Noun) — United States lawyer and poet who wrote a poem after witnessing the British attack on Baltimore during the War of 1812; the poem was later set to music and entitled 'The Star-Spangled Banner' (1779-1843).
key (Noun) — Metal device shaped in such a way that when it is inserted into the appropriate lock the lock's mechanism can be rotated.
key (Noun) — One of several labelled buttons on a typewriter, computer keyboard, or keypad, used to enter a particular character or invoke a particular function.
key (Noun) — Something crucial for explaining. ex. "the key to development is economic integration"
key (Noun) — Pitch of the voice. ex. "he spoke in a low key"
key (Noun) — Any of 24 major or minor diatonic scales that provide the tonal framework for a piece of music.
key (Noun) — A kilogram of a narcotic drug. ex. "they were carrying two keys of heroin"
key (Noun) — A winged often one-seed indehiscent fruit as of the ash, elm or maple.
key (Noun) — A coral reef off the southern coast of Florida.
key (Noun) — (basketball) a space (including the foul line) in front of the basket at each end of a basketball court; usually painted a different colour from the rest of the court. ex. "he hit a jump shot from the top of the key"
key (Noun) — A list of answers to a test. ex. "some students had stolen the key to the final exam"
key (Noun) — A list of words or phrases that explain symbols or abbreviations.
key (Noun) — A generic term for any device whose possession entitles the holder to a means of access. ex. "a safe-deposit box usually requires two keys to open it"
key (Noun) — Mechanical device used to wind another device that is driven by a spring (as a clock).
key (Noun) — The central building block at the top of an arch or vault.
key (Adjective) — Serving as an essential component. ex. "a key rule"
key (Verb) — Classify or apply the appropriate name to, e.g. in botany or biology.
key (Verb) — Provide with a key. ex. "We were keyed after the locks were changed in the building"
key (Verb) — Vandalize a car by scratching the sides with a key. ex. "His new Mercedes was keyed last night in the parking lot"
key (Verb) — (music) regulate the musical pitch of.
key (Verb) — Harmonize with or adjust to. ex. "key one's actions to the voters' prevailing attitude"