All four words describe converting data into a different form, but encryption specifically involves a secret key or password that controls who can reverse the process. Encoding is a broader term — a text file saved as UTF-8 is encoded but not encrypted. Ciphering is a more technical term that refers strictly to applying a cipher algorithm (e.g. AES-256) to data. Scrambling is informal and focuses on the visible result (data looks jumbled) rather than the mathematical process. For example, a messaging app uses encryption to protect conversations, while a computer scrambles the pixels on a damaged screen — only the first involves controlled access.
Derived from the verb 'encrypt', which was formed in the mid-20th century by combining the prefix 'en-' (to put into) with 'crypt', from Greek 'kryptos' meaning 'hidden'. The word was coined to describe the process of converting data into a hidden, coded form, especially for electronic communication.