ENGLISH n. The source code for a program, which may be in any language, as opposed to BINARY. Usage: slightly obsolete, used mostly by old-time hackers, though recognizable in context. At MIT, directory SYSENG is where the "English" for system programs is kept, and SYSBIN, the binaries. SAIL has many such directories, but the canonical one is [CSP,SYS]. EPSILON [from standard mathematical notation for a small quantity] 1. n. A small quantity of anything. "The cost is epsilon." 2. adj. Very small, negligible; less than marginal (q.v.). "We can get this feature for epsilon cost." 3. WITHIN EPSILON OF: Close enough to be indistinguishable for all practical purposes. EXCH (ex'chuh, ekstch) [from the PDP-10 instruction set] v. To exchange two things, each for the other. EXCL (eks'cul) n. Abbreviation for "exclamation point". See BANG, SHRIEK, WOW. EXE (ex'ee) See BIN.