(transitive) hang (a picture, etc.); hoist; raise (a flag); fly (a kite) / (transitive) multiply / to wear a piece of clothing / to pun (謎掛け) / to sit (on a chair or bench, but not on the floor)

(mathematics) times (multiplication)

a fragment; a splinter; a crumb

black key (of a piano, etc.)

white key (of a piano, etc.)

(Internet slang) protected account (on social media, especially Twitter and Instagram)

(idiomatic) to hold the key (to)

(cryptography) secret key

(cryptography) public key

(cryptography) key exchange - an exchange of peers' keys at initialization phase of connection.