hash key is an element in the hash table. it is the data that you will combine (mathematical) with hash function to produce the hash.

Potatoes

hash passwords - contraseñas hash

It makes a big difference because if you compared the hash:

abcde.fg = hash 1

to

abcdefg = hash 3

The results hash 1 and hash 3 are not equal.

The output from a hash function is referred to as the hash value, hash code, hash sum, checksum or just plain "hash" as in "the hash of the file is...". Generally a hash function is presumed to be secure or it wouldn't be used. If a hash is not secure it could be referred to as "worthless" or "false sense of security".