Final answer:
The cipher type that processes large segments of a message as a whole unit, rather than on a bit-by-bit or character-by-character basis, is known as a Block cipher. Block ciphers, such as the AES, encrypt fixed-size blocks of plaintext, unlike stream ciphers or the Caesar cipher which work on individual elements.
Step-by-step explanation:
The cipher type that operates on large pieces of a message rather than individual characters or bits of a message is the Block cipher. Unlike stream ciphers, which encrypt data bit by bit or character by character, block ciphers take a block of plaintext and encrypt it as a single unit, applying the cipher to a group of bits. Block ciphers can use various sizes of blocks, but each block is typically of a fixed size. A popular example of a block cipher is the Advanced Encryption Standard (AES).
The Transposition Cipher, which was mentioned in relation to the Zimmerman Telegram, is a type of block cipher where the positions of the characters in the plaintext are shuffled according to a defined system, sometimes utilizing a keyword. However, it does not encrypt the characters themselves but rather rearranges them. Block ciphers can also use more complex algorithms and typically employ a symmetric key for both encryption and decryption.