awk
1. <tool, language> (Named from the authors' initials) An interpreted language included with many versions of Unix for massaging text data, developed by Alfred Aho, Peter Weinberger, and Brian Kernighan in 1978. It is characterised by C-like syntax, declaration-free variables, associative arrays, and field-oriented text processing.
There is a GNU version called gawk and other varients including bawk, mawk, nawk, tawk. Perl was inspired in part by awk but is much more powerful.
Unix manual page: awk(1).
["The AWK Programming Language" A. Aho, B. Kernighan, P. Weinberger, A-W 1988].
2. <jargon> An expression which is awkward to manipulate through normal regexp facilities, for example, one containing a newline.