1) French word used in English 
In cryptography, FEAL (the Fast data Encipherment ALgorithm) is a block cipher proposed as an alternative to the Data Encryption Standard (DES), and designed to be much faster in software. The Feistel based algorithm was first published in 1987 by Akihiro Shimizu and Shoji Miyaguchi from NTT. The cipher is susceptible to various forms of cryptanal...
• (a.) Faithful; loyal.
Fe'al adjective [ Old French feal , feel , feeil , fedeil , French fidèle , Latin fidelis faithful, from fides faith. See Faith .] Faithful; loyal. [ Obsolete] Wright. 
Feal is Northern and Midlands British slang for to hide or conceal.