Pronunciation: [kˈiːhə͡ʊl] (IPA) 
The spelling of the word "keyhole" is rather straightforward. The first syllable, "key," is spelled as it sounds. The second syllable, "hole," is spelled with the "o" and "e" joined together to make the sound /oʊ/. Therefore, the IPA phonetic transcription of "keyhole" would be /kiːhoʊl/. This word is often used to describe the small, round opening in a lock that a key fits into to gain entry.
Keyhole, noun: (1) A small, often circular or oval aperture in a door, lock, or other barrier, usually at eye level, through which a key may be inserted to lock or unlock the mechanism. (2) A small hole or opening shaped like a keyhole, typically found in various objects, used for observation or viewing purposes. (3) A surgical procedure or technique in which a small incision is made in the skin, resembling the shape of a keyhole, in order to access and perform operations on internal organs or tissues. (4) In astronomy, a term referring to a type of telescope or instrument that provides a narrow and magnified view of celestial objects, resembling the shape of a keyhole. (5) A metaphorical term suggesting a means of access or entry into a particular situation or understanding, usually involving obtaining exclusive or hidden information. (6) In street layouts or urban planning, a narrow, partially enclosed lane or alley that allows access to a row of buildings or residences, typically located behind a main street or road. (7) In computer science or cryptography, a type of encryption or decryption algorithm that utilizes a key to transform plaintext into ciphertext and vice versa, ensuring secure and private communication or data storage.
The word "keyhole" originated from the combination of two Old English words. The first element, "key", comes from the Old English word "cǣg" or "cǣge", which means "key" or "bolt". The second element, "hole", comes from the Old English word "hol", which means "cavity" or "opening". The term "keyhole" was first recorded in the English language around the 14th century, referring to the opening or cavity where a key is inserted to operate a lock.
